- When flowing liquid starts to flow down, it stops contributing to its neighboring nodes' liquid level (possibly transforming it back to air)
- Flowing liquid turns into a source if there are at least 2 adjacent liquid source nodes
- If a new liquid flow reaches existing flowing liquid, the existing liquid is now updated properly.

Upstream merge

Conflicts:
	.gitignore
	CMakeLists.txt
	data/heart.png
	src/CMakeLists.txt
	src/game.cpp
	src/guiMainMenu.cpp
	src/inventory.cpp
	src/map.cpp
	src/mapblock.cpp
	src/mapnode.cpp
	src/mapnode.h
	src/materials.cpp
	src/server.cpp

Signed-off-by: Sebastian Rühl <bahamada_basti@yahoo.de>

New map generator added (and SQLite, messed up the commits at that time...) (import from temporary git repo)