Move decl_impl example to specific folder

And extend the class example to have an impl file as well for
testing.
Update gitignore files to have clean repository

Tired of stuff lying around confusing the status but still want some of
that stuff for development.
Improve function argument handling for overloads

The previous approach tried to read appropriate data out of the xml
object hierarchy and use it to figure out which function overload to
use. Unfortunately it only looked at the first entry and so for 'const'
declarations it would only see the word 'const' rather than a useful
type.

Here we introduce a TextRenderer based on Sphinx's text rendering
functionality and use it to render the xml arguments to a text string
and then do the comparisons based on comparing that to the input string
of the directive. Should prove more accurate.
Add no-link options to clean up some warnings
Display potential matches when function arg matching fails
Fix documentation to reference correct args