Release concept: to discuss and improve about reg-gen

[fabio-t]

The current approach of using one release version for all tools in the RGT toolbox seem to be very efficient.

One possible future modification is the following:

• split rgt-core, the actual library, from the tools
• each tool becomes its own python package (eg either called like rgt-THOR or just THOR)
• each tools has its own dependencies, but they all depend on rgt-core. There should never be inter-tool dependencies
• rgt-core and each tool keep their own versions and changelogs, and with time they can detach from the "rgt umbrella" to become their own isolated thing, if they get big/influential enough. Right now this isn't possible in a clean way

This would allow users to only install the tool they are actually interested in, or even just use rgt-core for their own tools.

I would see this being a single github repository with one submodule for each tool and one for rgt-core.