Speed up removing a node (less block mesh updates).
Add mgv5. New noise code, uses biome API. Eased 3d noise for terrain, caves, blobs
Fix regressions and minor improvements in refactor_the_game
a) Fix double tap for jump and show_debug
b) Revert changes to limitFps()... there is no verification that the new method was an issue, but going back to old method just in case
b.2) limitFps() no longer calls device->run() and also no longer has to be called immediately after a call to device->run()
Stop inserting empty lines at end of minetest.conf file each time it is rewritten

See: https://github.com/minetest/minetest/issues/1790
Merge remote-tracking branch 'minetest/master' into master2