* Fix automatic generation of spatial function types files
The automatic mapping of spatial function names from class names was not working for spatial types, so the automatic generation of these files did not happen, and in fact existing files were deleted.
In addition, the generation of aggregation functions types does not yet exist at all, so the st_centroid.asciidoc file was always deleted. Until such support exists, this files contents will be moved back into the function definition file.
The railroad diagrams for syntax are now also created, however, not all functions in the documentation actually use these, and certainly none of the `TO_*` type-casting functions do, so we'll not include links to them from the docs, and leave that to the docs team to decide. Personally, while these diagrams are pretty, they contain no additional informational content, and in fact give a cluttered impression to the documentation visual appeal.
* Refined to use an annotation which is more generic
