Merge branch 'feature/sdl2'

Merge branch 'feature/sdl2'

Conflicts:
	.gitignore
	WHATSNEW.txt
	data/fonts/zh-white-big.stf
	data/fonts/zh-white.stf
	data/images/engine/fonts/zh/shadow.png
	data/images/engine/fonts/zh/white.png
	data/images/powerups/egg/egg.sprite
	data/images/tiles.strf
	data/levels/bonus1/az.po
	data/levels/bonus1/ne.po
	data/levels/bonus1/sv.po
	data/levels/bonus2/az.po
	data/levels/bonus2/pt_BR.po
	data/levels/incubator/az.po
	data/levels/incubator/de.po
	data/levels/incubator/nn.po
	data/levels/incubator/pt_BR.po
	data/levels/incubator/ru.po
	data/levels/incubator/sv.po
	data/levels/incubator/worldmap.stwm
	data/levels/world1/ar.po
	data/levels/world1/az.po
	data/levels/world1/be.po
	data/levels/world1/ca.po
	data/levels/world1/cmn.po
	data/levels/world1/cs.po
	data/levels/world1/da.po
	data/levels/world1/de.po
	data/levels/world1/el.po
	data/levels/world1/eo.po
	data/levels/world1/es.po
	data/levels/world1/et.po
	data/levels/world1/fi.po
	data/levels/world1/fr.po
	data/levels/world1/hi_IN.po
	data/levels/world1/hr.po
	data/levels/world1/hu.po
	data/levels/world1/it.po
	data/levels/world1/ja.po
	data/levels/world1/lt.po
	data/levels/world1/nb.po
	data/levels/world1/ne.po
	data/levels/world1/nl.po
	data/levels/world1/nn.po
	data/levels/world1/pl.po
	data/levels/world1/pt.po
	data/levels/world1/pt_BR.po
	data/levels/world1/ro.po
	data/levels/world1/ru.po
	data/levels/world1/sl.po
	data/levels/world1/sv.po
	data/levels/world1/tr.po
	data/levels/world1/uk.po
	data/levels/world1/uz.po
	data/levels/world1/vi.po
	data/levels/world1/zh_CN.po
	data/levels/world1/zh_TW.po
	data/levels/world2/az.po
	data/levels/world2/cs.po
	data/levels/world2/de.po
	data/levels/world2/hu.po
	data/levels/world2/nn.po
	data/levels/world2/pt_BR.po
	data/levels/world2/sv.po
	data/locale/ar.po
	data/locale/az.po
	data/locale/be.po
	data/locale/ca.po
	data/locale/cmn.po
	data/locale/cs.po
	data/locale/da.po
	data/locale/de.po
	data/locale/el.po
	data/locale/eo.po
	data/locale/es.po
	data/locale/et.po
	data/locale/fi.po
	data/locale/fr.po
	data/locale/hi_IN.po
	data/locale/hr.po
	data/locale/hu.po
	data/locale/it.po
	data/locale/ja.po
	data/locale/lt.po
	data/locale/nb.po
	data/locale/ne.po
	data/locale/nl.po
	data/locale/nn.po
	data/locale/pl.po
	data/locale/pt.po
	data/locale/pt_BR.po
	data/locale/ro.po
	data/locale/ru.po
	data/locale/sl.po
	data/locale/sv.po
	data/locale/tr.po
	data/locale/uk.po
	data/locale/uz.po
	data/locale/vi.po
	data/locale/zh_CN.po
	data/locale/zh_TW.po
	external/squirrel/squirrel/sqdebug.cpp
	src/object/bonus_block.cpp
	src/object/explosion.cpp
	src/object/player.cpp
	src/supertux/game_session.cpp
	src/supertux/level.cpp
	src/supertux/main.cpp
	src/supertux/resources.cpp
	src/video/sdl/sdl_renderer.cpp
	src/worldmap/worldmap.cpp