terminal.c - render_terminal() - Clean & improve this function

[kerrambit]

terminal.c - render_terminal() - Clean & improve this function There must be certain things done related to this:

1. add different colours that user can choose
2. when setting up the terminal, the default message for special_regime can be decided
3. terminal should be also able to say exactly which command was wrong etc. - this involves also for easy string creating (something like sprintf)

[kerrambit]

Done.