Don't fontify "stdin:N:" stacktrace entries in REPL buffer

Add couple of minor tweaks here and there on the way.
Reimplement customized rx on top of ample-regexps
lua-rx: fix a typo in group-n definition
lua-rx: fix lua-name definition
Use lua-rx for Lua builtin matchers
Use lua-rx for multiline literal matchers
Use lua-rx for continuation line matchers
Use lua-rx for indentation modifier matchers
Disable fontification of "stdin:N" via advice, not regexp

The regexp turned out to be magic (unstable), any change in it caused
breakage.
Use lua-rx for traceback & prompt matchers