MPS-17904 Add validation to Generator Priorities module properties page
MPS-17652 generator priorities: problems with editing
Merge branch 'master' into 3.0/victor/bugs

Conflicts:
	workbench/mps-ui/models/jetbrains/mps/ide/ui/dialogs/properties/editors.mps
	workbench/mps-ui/models/jetbrains/mps/ide/ui/dialogs/properties/renderers.mps