Enable structure view for the MPS nodes
Missing data provider interface for FileEditor
Attempting to make navbar usable with MPS editors
Attempting to make navbar usable with MPS editors (fix)
Compilation fix
Reimplemented children list in MPSPsiNodeBase, cleaning up the API
Merge remote branch 'origin/master' into fisakov/psi

Conflicts:
	IdeaPlugin/mps-core/src/jetbrains/mps/idea/core/psi/impl/MPSPsiNodeBase.java
	IdeaPlugin/mps-core/src/jetbrains/mps/idea/core/psi/impl/MPSPsiProvider.java
	workbench/mps-editor/source/META-INF/MPSEditor.xml
Non-essential update