Massive restructuring: A unified interface, the ‘defblock’ macro, for making new block and link types.
We preprocess Org before export to perform arbitrary computations on special blocks
that may have arguments ---similar in spirit to Org-Babel's src blocks ;-)
The resulting framework is "familiar" to use, no strange new syntax required, and immediately
extensible using defblock ---which is similar to defun.
This system was featured in EmacsConf2020.