fixed crash in plugin destructor
fixed compilation not being freed causing a crash
fixed small issues in plugin system
fixed plugin iterator not being reseted when freed and not being initialized it's current pointer.
fixed a bug where insertion of a prefixed string would not check whether a value could be set.
--HG--
extra : convert_revision : svn%3A39bc706e-5318-0410-9160-8a85361fbb7c/trunk%40221