XCOMMONS-674: Occasional rendering problem when viewing FlamingoThemes.FlamingoDefaultTheme
XCOMMONS-673: DefaultVelocityEngine is doing a lot of locking

(cherry picked from commit 11071d1c7be4dfd35d6cca9f9dafb450e8b9ecb5)

Conflicts:
	xwiki-commons-core/xwiki-commons-velocity/src/test/java/org/xwiki/velocity/internal/DefaultVelocityEngineTest.java