Add definable node_stone to biome API, mgv5, mgv7. Reduce and correct depth of mgv7 biomes. l_mapgen.cpp: add '#include mapgen_v5.h' because '#include mapgen_v7' is there. Improve underwater grass hack
Settings: Various setting group fixes and enhancements

 - Remove blank setting values when setting has a group
 - Pair setting values with groups in file when possible
 - Preserve user-set whitespace in setting objects
 - Delete setting value when setting NoiseParams group
 - Delete overwritten groups outside of lock
Make dropped items larger and rotate faster

Signed-off-by: Craig Robbins <kde.psych@gmail.com>
Right mouse button behaviour for craft/inventory If right mousebutton clicked once then don't drop single items into slots. If right mouse button has been clicked and held a second time, drop items as the mouse is moved. In the second case (automatically drop/place items as mouse is moved) only auto-drop into blank slots, or slots that contain the same item.
Optimise VoxelManipulator::copyFrom

~3-4x faster

This indirectly optimises MapBlock:copyTo() which in turn improves performance of MeshMakeData::fill()
(INTERIM) Make sizes of the font in formspecs consistent and not so large

Until a permanent fix can be developed
Recalculate normals for mesh #0. Fix for issue #1902.