Updated to work with 1.6.
Added in proper versioning so that the 1.4 and 1.5 versions should still be operational.

Checked that it's still working on the early access 1.5 version, and it seems to be fully operational.

Cleaning now should properly take into account mechanoids, slaves and pawns that cannot do Cleaning work.

Cleaning amount now actually depends on General Labor Speed.
Fixed caching of cleaning amount.
Fixed off-by-one errors when cleaning stops when finished/etc.

[Auto-generated text]: Initial upload.