serialization NPE: more diagnostics
move annotation filtering logic to completion contributors
more concise tests
add APPLICATION_PLUGINS_DIR predefined path variable (IDEA-101030)
garbageless jdom hash calculation
Revert: IDEA-110625 External system: Add git root automatically on linking external project (1815ffc)

The problem is that one of platform modules (external-system-impl) depends on plugin module (git4idea) now. We want to avoid that by moving common api part to vcs-api and providing vcs-specific support via extension points