Don't use regex, use read
Refrain from evaluating buffer

Evaluating the buffer requires that all required libraries and functions
are present at the moment the documentation is generated. Because
documentation generation may happen in an Emacs without X11 support or
without all the libraries installed, this is not an optimal solution.
Remove obsolete function
Fix referencing function names
Don't include undocumented items

They were already not printed, but they were still indexed. Not indexing
them keeps them from being linked to in other parts of the
documentation.