maker.py: Adds WIP overlay type checking
maker.py: Rewords source URL amount prompt
maker.py: Adds overlay type confirmation checking
maker.py: Adds overlay package adding to xml
maker.py: Adds explicit file path declaration for write()

write() will now also return a boolean to indicate a successful
write to.
maker.py: Implements reload_config() function
maker.py: Adds autofill support for select mirrors

github.com, and git.overlays.gentoo.org mirrors will have
their extra source URLs, homepage, and feeds filled out
for them automatically.
maker.py: Alters file output path to overlay-defs
Adds proper feed support for overlay dicts
overlay.py: Removes old branch tag components

In favor of setting the branch variable in each source tag, the old
branch tag components have been removed.