Rename some doc/misc info nodes to avoid chars that can cause Texinfo problems

Rename some doc/misc info nodes to avoid chars that can cause Texinfo problems

* reftex.texi (LaTeX xr Package, Options - Table of Contents)
(Options - Defining Label Environments, Options - Creating Labels)
(Options - Referencing Labels, Options - Creating Citations)
(Options - Index Support, Options - Viewing Cross-References)
(Options - Finding Files, Options - Optimizations)
(Options - Fontification, Options - Misc):
* cc-mode.texi (Sample Init File):
* edt.texi (Init file):
* epa.texi (Encrypting/decrypting gpg files):
* mairix-el.texi (About, Setting up the mairix interface, Using)
(Extending):
Rename nodes to avoid characters that can cause Texinfo problems.