Fix some problems with the User's guide.

doc/user_guide.texi:
	Delete a reference to `:' as a module qualifier.

	Comments in texinfo begin with "@c", not "%".

	Fix an ordering mismatch between the menu and the sectioning:
	``Build options'' and ``Miscellaneous options'' should
	occur *after* ``Link options''.
Fix warnings from texinfo in User's guide.

doc/user_guide.texi:
	Fix spots where there were ordering mismatches between the menus and the
	sectioning.
Fix warnings from texinfo in the reference manual.

doc/reference_manual.texi:
	Fix the ordering of the menu in the foreign language interface
	chapter so that it matches the sectioning.