Add sol.main.get_os() function. Fix https://github.com/christopho/solarus/issues/562
Remove the empty directory
make_solarus_tools_src_package made.
Merge pull request #605 from Nate-Devv/master

Remove the empty directory
Merge pull request #597 from christopho/get_os

Add sol.main.get_os() function.
Update changelog about new function sol.main.get_os().
Add missing include.
Fix hero freeze when a treasure's dialog is missing. Fix #595.
Fix tunic and sword collision when their sprite is changed. Fix #617.
Fix crash when a tileset image is missing. Fix #590.
Merge branch 'master' into cpp11

Conflicts:
	include/lowlevel/System.h
	src/entities/Hero.cpp
	src/entities/Pickable.cpp
	src/entities/Tileset.cpp
	src/lua/EntityApi.cpp
	src/lua/MainApi.cpp