[emacs] Remove risc-mode.el

I have stopped using it a long while ago, and I guess people who like
the idea can use viper or whatever.
[emacs] Load local.el at the very end
[emacs] Removed unused and redundant code plus small improvements

Mostly removing of code that I've used for a very long while (or
have never used at all) and code that sets variable to its
default value which is redundant.

Beside that some small improvements (e.g. use of `bound-and-true-p`)
and some changes which try to get rid of various compiler warnings.