Improvements to test runner
Improvements to test runner

Put generated js in temp dir and only delete it if test succeeds.
Exit with code 1 if some tests failed
Add an option to only run a specific test file

kovidgoyal/rapydscript-ng,kovidgoyal/RapydScript,atsepkov/RapydScript,kovidgoyal/rapydscript-ng,kovidgoyal/rapydscript-ng,atsepkov/RapydScript,atsepkov/RapydScript,kovidgoyal/rapydscript-ng,kovidgoyal/RapydScript,kovidgoyal/RapydScript