Add --script-all-dialogue switch to test compilation of dialogue scripts

See comment on https://bugs.openmw.org/issues/1659 for more background. 

I tested this implementation on the MW localisations that I have access to via Steam (german, english and french) and found several errors, not all of which are errors in original MW. I created a wiki page to keep track of them: https://wiki.openmw.org/index.php?title=Dialogue_script_bugs
If anyone has access to other localisations, testing them would be great.