Cleaning up unused code in meta

[syclik]

Summary

Removes unused meta traits from code.

These are template metaprograms not used anywhere in the codebase. Some of the functionality has been replaced with newer require_* traits.

runTests.py has been updated for the --changed tests. Removal of tests results in the test being called. This was fixed using --diff-filter=d which excludes deleted files.

Tests

No new tests. There is no additional behavior.

Side Effects

External calls to these traits will break. These are not used within Stan and Math (anymore) and can be removed safely without affecting the Stan ecosystem.

Release notes

Removing unused template metaprograms.

Checklist

• Copyright holder: Daniel Lee

  The copyright holder is typically you or your assignee, such as a university or company. By submitting this pull request, the copyright holder is agreeing to the license the submitted work under the following licenses:
  - Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
  - Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

• the basic tests are passing

  • unit tests pass (to run, use: ./runTests.py test/unit)
  • header checks pass, (make test-headers)
  • dependencies checks pass, (make test-math-dependencies)
  • docs build, (make doxygen)
  • code passes the built in C++ standards checks (make cpplint)

• the code is written in idiomatic C++ and changes are documented in the doxygen

• the new changes are tested

[WardBrian]

Nice cleanups, and thanks for the patch to runTests.