Bugfixes.

Fixed #264
Fixed #232
Fixed #228
Fixed #101

Adds a new helper proc, isinspace(), which checks if get_turf(src) is a turf/space.

Commits were cherry-picked from awyeahmuthafuckingbugfixes, PR #1675. (Except for the last one)

git is cool when it works, but when it doesn't it's AGHAIEIGPIJDPIJGIOAPJDIJGAIDGHAIODGHDIJDIOGJPIEUAIOGHPDIHGAI.

Yes I know one of the commits says [MAP] but that commit is a dirty liar.