Allow cactus to lay on its side also.
Rewrite player.lua
Fix indentation, use log() instead of print() and use get_item_group() in tree growing ABM
Remove / replace all print() calls
Add is_ground_content setting to grass_1, apple, and dry shrubs
Explicitly set values of is_ground_content

Counterpart commit to minetest 9a927476
Add waving property for leaves and plants.