gplugin/gplugin

Simplify shared library versioning.
develop
2017-06-09, Elliott Sales de Andrade
06217d1664be
Simplify shared library versioning.

Meson isn't libtool so we don't really need to use the same current,
age, revision thing. Also, the 'soversion' property defaults to the
first element of 'version', so we don't need to specify it.
There are a few notes about building on OSX.
First off, building has *ONLY* been tested against homebrew. If you want to
support fink or macports, please let me know and I will merge your pull
request.
Lua
===
For the Lua loader to work, you need to install lgi from luarocks either
systemwide or to a virtual environment created by LuaDist, vert, or something
along those lines.
When you're building lgi against homebrew you'll have to set the
PKG_CONFIG_PATH environment variable since homebrew does not install libffi
systemwide. This is easily done via:
export PKG_CONFIG_PATH=$(brew --prefix libffi)/lib/pkgconfig
and then running "luarocks install lgi"
PYTHON
======
If you're using homebrew, you need to install pygobject3 with
brew install pygobject3 --with-python3