New entity type: camera stoppers (not finished yet).
Merge branch 'master' into v1.1
Merge branch 'master' into v1.1

Conflicts:
	developer_doc/Doxyfile
	doc/Doxyfile
Merge branch 'master' into v1.1
Editor: fix a possible NullPointerException when opening an invalid map.
Basic but working implem of camera stoppers (no scrolling yet). #177
Add camera stoppers to the editor (#177).
Merge branch 'master' into v1.1

Conflicts:
	ChangeLog
	src/entities/MapEntities.cpp
Merge branch 'master' into v1.1
Document camera stoppers in the map data file syntax (#177).
Update the format number of the editor.
Handle camera stoppers that don't traverse the whole map (#177).
Add a flag to force VideoManager::is_mode_supported()
Handle not-defined case for SOLARUS_FORCE_ALL_VIDEOMODE
Add SOLARUS_FORCE_ALL_VIDEOMODE flag into Common file
Set default fullscreen size if not supported
Set SOLARUS_FORCE_ALL_VIDEOMODE correctly
Default fullscreen size is the double of default size
Change "force fullscreen" flag name
SOLARUS_FULLSCREEN_FORCE_OK only affect fullscreen mode