regex engine - simplify regnode structures and make them consistent

This eliminates the regnode_2L data structure, and merges it with the older
regnode_2 data structure. At the same time it makes each "arg" property of the
various regnode types that have one be consistently structured as an anonymous
union like this:

    union {
        U32 arg1u;
        I32 arg2i;
        struct {
            U16 arg1a;
            U16 arg1b;
        };
    };

We then expose four macros for accessing each slot: ARG1u() ARG1i() and
ARG1a() and ARG1b(). Code then explicitly designates which they want. The old
logic used ARG() to access an U32 arg1, and ARG1() to access an I32 arg1,
which was confusing to say the least. The regnode_2L structure had a U32 arg1,
and I32 arg2, and the regnode_2 data strucutre had two I32 args. With the new
set of macros we use the regnode_2 for both, and use the appropriate macros to
show whether we want to signed or unsigned values.

This also renames the regnode_4 to regnode_3. The 3 stands for "three 32-bit
args". However as each slot can also store two U16s, a regnode_3 can hold up
to 6 U16s, or as 3 I32's, or a combination. For instance the CURLY style nodes
use regnode_3 to store 4 values, ARG1i() for min count, ARG2i() for max count
and ARG3a() and ARG3b() for parens before and inside the quantifier.

It also changes the functions reganode() to reg1node() and changes reg2Lanode()
to reg2node(). The 2L thing was just confusing.

embed.fnc

@@ -5141,9 +5141,6 @@ ES	|regnode_offset|reg	|NN RExC_state_t *pRExC_state		\
 				|I32 paren				\
 				|NN I32 *flagp				\
 				|U32 depth
-ES	|regnode_offset|reganode|NN RExC_state_t *pRExC_state		\
-				|U8 op					\
-				|U32 arg
 ES	|regnode_offset|regatom |NN RExC_state_t *pRExC_state		\
 				|NN I32 *flagp				\
 				|U32 depth
@@ -5167,11 +5164,6 @@ ES	|void	|reginsert	|NN RExC_state_t *pRExC_state		\
 				|const U8 op				\
 				|const regnode_offset operand		\
 				|const U32 depth
-ES	|regnode_offset|reg2Lanode					\
-				|NN RExC_state_t *pRExC_state		\
-				|const U8 op				\
-				|const U32 arg1 			\
-				|const I32 arg2
 ES	|regnode_offset|reg_la_NOTHING					\
 				|NN RExC_state_t *pRExC_state		\
 				|U32 flags				\
@@ -5180,6 +5172,13 @@ ES	|regnode_offset|reg_la_OPFAIL					\
 				|NN RExC_state_t *pRExC_state		\
 				|U32 flags				\
 				|NN const char *type
+ES	|regnode_offset|reg1node|NN RExC_state_t *pRExC_state		\
+				|U8 op					\
+				|U32 arg
+ES	|regnode_offset|reg2node|NN RExC_state_t *pRExC_state		\
+				|const U8 op				\
+				|const U32 arg1 			\
+				|const I32 arg2
 ES	|regnode_offset|reg_node|NN RExC_state_t *pRExC_state		\
 				|U8 op
 ES	|regnode_offset|regnode_guts					\

embed.h

@@ -1845,13 +1845,13 @@
 #     define parse_lparen_question_flags(a)     S_parse_lparen_question_flags(aTHX_ a)
 #     define parse_uniprop_string(a,b,c,d,e,f,g,h,i,j) S_parse_uniprop_string(aTHX_ a,b,c,d,e,f,g,h,i,j)
 #     define reg(a,b,c,d)                       S_reg(aTHX_ a,b,c,d)
-#     define reg2Lanode(a,b,c,d)                S_reg2Lanode(aTHX_ a,b,c,d)
+#     define reg1node(a,b,c)                    S_reg1node(aTHX_ a,b,c)
+#     define reg2node(a,b,c,d)                  S_reg2node(aTHX_ a,b,c,d)
 #     define reg_la_NOTHING(a,b,c)              S_reg_la_NOTHING(aTHX_ a,b,c)
 #     define reg_la_OPFAIL(a,b,c)               S_reg_la_OPFAIL(aTHX_ a,b,c)
 #     define reg_node(a,b)                      S_reg_node(aTHX_ a,b)
 #     define reg_scan_name(a,b)                 S_reg_scan_name(aTHX_ a,b)
 #     define reg_skipcomment                    S_reg_skipcomment
-#     define reganode(a,b,c)                    S_reganode(aTHX_ a,b,c)
 #     define regatom(a,b,c)                     S_regatom(aTHX_ a,b,c)
 #     define regbranch(a,b,c,d)                 S_regbranch(aTHX_ a,b,c,d)
 #     define regclass(a,b,c,d,e,f,g,h,i)        S_regclass(aTHX_ a,b,c,d,e,f,g,h,i)

pod/perldebguts.pod

@@ -752,13 +752,13 @@ will be lost.
  PLUS             node       Match this (simple) thing 1 or more times:
                              /A{1,}B/ where A is width 1 char
 
- CURLY            sv 4       Match this (simple) thing {n,m} times:
+ CURLY            sv 3       Match this (simple) thing {n,m} times:
                              /A{m,n}B/ where A is width 1 char
- CURLYN           no 4       Capture next-after-this simple thing:
+ CURLYN           no 3       Capture next-after-this simple thing:
                              /(A){m,n}B/ where A is width 1 char
- CURLYM           no 4       Capture this medium-complex thing {n,m}
+ CURLYM           no 3       Capture this medium-complex thing {n,m}
                              times: /(A){m,n}B/ where A is fixed-length
- CURLYX           sv 4       Match/Capture this complex thing {n,m}
+ CURLYX           sv 3       Match/Capture this complex thing {n,m}
                              times.
 
  # This terminator creates a loop structure for CURLYX
@@ -796,7 +796,7 @@ will be lost.
 
  # Support for long RE
  LONGJMP          off 1 1    Jump far away.
- BRANCHJ          off 2L 1   BRANCH with long offset.
+ BRANCHJ          off 2 1    BRANCH with long offset.
 
  # Special Case Regops
  IFMATCH          off 1 1    Succeeds if the following matches; non-zero
@@ -814,7 +814,7 @@ will be lost.
  # The heavy worker
 
  EVAL             evl/flags  Execute some Perl code.
-                  2L
+                  2
 
  # Modifiers
 
@@ -825,7 +825,7 @@ will be lost.
  RENUM            off 1 1    Group with independently numbered parens.
 
  # Regex Subroutines
- GOSUB            num/ofs 2L recurse to paren arg1 at (signed) ofs arg2
+ GOSUB            num/ofs 2  recurse to paren arg1 at (signed) ofs arg2
 
  # Special conditionals
  GROUPPN          no-sv 1    Whether the group matched.
@@ -836,7 +836,7 @@ will be lost.
  ENDLIKE          none       Used only for the type field of verbs
  OPFAIL           no-sv 1    Same as (?!), but with verb arg
  ACCEPT           no-sv/num  Accepts the current matched string, with
-                  2L         verbar
+                  2          verbar
 
  # Verbs With Arguments
  VERB             no-sv 1    Used only for the type field of verbs