typos: fix typos in several locations A user at Google attempted to fix our local copy because they had noticed a typo (accross instead of across), but this will just get overwritten on our next import. This commit fixes that case and a few others that my editor found. Most of the typos were in comments, but user-visible output is changed in a few cases: - accross -> across - splitted -> split - ambigious -> ambiguous - evolvestte -> evolvestate (this is in a ui.debug, so not often seen) There is another typo that I wanted to fix, but didn't: 'supercede' is spelled 'superseed' in a few locations. I believe this is only internal to the extension, instead of being user-visible, so while it could probably be fixed easily, I wasn't 100% sure it didn't end up in a file on disk or something and might cause problems, so I left it alone.