Rename to beam_red

[jannikbecher]

Since this tool is based on the BEAM and it could be possible to extend the tool by other beam languages, maybe it is a good idea to rename it to the more general name "beam_red"?

[gorenje]

I did think about it but no, I'll stick to Erlang-RED.

It's Erlang first but does support other Beam languages but it's not coded in Beam, it's coded in Erlang.

Besides if someone wishes to create an Elixir-RED using the flow tests as a guide there woud be two beam reds - beam me up scotty! ;)