Run command no longer overwrites document

Previously the run command would take care of saving the document rather than rely on TextMate to do this. The reason for this was to allow executing untitled documents as scripts (without asking the user to first save the script).

With TextMate 2 we no longer ask for a file name when using the “Save: Modified Documents” option, so the run command now only takes care of saving, if the document is untitled (in which case, it writes it to a temporary file and executes that).