Break out in many repos, and support building from sources all the way.

[pombredanne]

The current setup can be improved:

1. for simplicity we should have one repo for each plugin rather than one big "mono" repo as we have to today. Each repo should be for all os/arch combos of a given plugin
2. we should be able to build from sources and may be use @altendkyhttps://github.com/altendky/romp to get native pre-built wheel for every os/arch combos ... (except possibly for FreeBSD?)

As a result, we should be able to publish on PyPI both the pre-built wheels and the sdists for each of these plugins.

For 2. we currently use prebuilts from homebrew for macOS, linuxbrew for Linux and msys2 for Windows. To build from sources we should try to execute these as part of the setup process.