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.
Adds multiple description field support

X-Gentoo-Bug: 465730
X-Gentoo-Bug-URL: https://bugs.gentoo.org/465730
maker.py: Adds stub function to grab descriptions

This function has been added in hopes of later adding multiple
description field support to the interactive overlay creation
session.
maker.py: Notifies user of location of successful write
maker.py: Adds "https://" source splitting support
maker.py: Adds Exception raising for errors