Seal's Gentoo overlay

Fixing random stuff here, as well as useful utils and other ebuild work.

Adding the repository

Add the following line to /etc/layman/layman.cfg's Overlays section:

https://github.com/seal331/gentoo-overlay/raw/master/repositories.xml

Then execute:

layman -f
layman -a seal331-gentoo

Syncing the repository

Easy, just execute layman -s seal331-gentoo.