Added binary generated files section to .gitignore

With the added section, any files that have been generated by the binary
may be safely ignored by git. Currently, the only files being generated
by the binary are .png files.
Added initial support for biomes (image colouring)

There have been several majour changes to the structure of mapGen to
include image colouring through the use of biomes. These changes have
also helped seperate the frontend from the library. As of this point in
time, image colouring is not working correctly.