Merge branch 'master' into gl
config.tests: cache done tests

mistake in commit 92d38af
config tests: remove existing value in cache for unix shell
config tests: fix build dir error
update build guide
Merge branch 'gl' of github.com:wang-bin/QtAV into gl
Merge branch 'master' into gl
use 'sed -i' on win is not a good idea

can not access the cache file when running qmake
Merge branch 'master' into gl
gl: add GL_BGRA. correct the base class