msb/deps/libpeas

Libpeas is a gobject-based plugins engine, and is targetted at giving
every application the chance to assume its own extensibility.
It also has a set of features including, but not limited to:
- multiple extension points
- on demand (lazy) programming language support for C, Python and JS
- simplicity of the API

python3 is an optional (autodetected) dependency.
other two are lgi and luajit: if you have both in you system just the
second is used.