v3.1.0-rc3

See the README more information.

Tl;dr: Single binary (don't need to clone the repo any more for it to work), many more options / flags, reduced ram required for tile generation stage (also meaning if it has to bleed over into swap for other parts of the programme the performance impact is not as bad as if it happens during tile generation), no longer have to do the full planet, more...

Testing ongoing with various configs over the next week or so.

Expected further improvement on go test and logging to be tidied up before release.

Comments, questions, bug reports etc all welcome :).