Deprecate more methods. Internal APIs have been verified to be unused
elsewhere and removed. External APIs have had deprecation methods added.
Existing deprecations have been either upgraded to produce warnings or
no longer deprecated and the reasoning documented.
GitHub provides a description and homepage field so let `brew create`
use them where possible. Also, detect GitHub repositories based on
`releases` as well as `archive`s.
meson is quickly gaining popularity as build system, in combination with
ninja. Several Gnome projects for example are currently transitioning
from autotools to meson, mostly because it allows for Visual Studio
builds, which is impossible to accomplish with autotools.
In order to facilitate generating meson based Formulas, I added support
for meson to brew-create.
