External system: code cleanup
IDEA-125749 Create New Class Dialog - Pressing 'e' in Kind selects 'Interface' instead of 'Enum'
IDEA-125442 Strip .java from classname when creating new class
always use forward slashes in copy reference (IDEA-125292)
don't advertise Quick Definition when completion doesn't contain psi items (IDEA-87208)
dfa: invalid type diagnostics (IDEA-125179)
javadoc fix
moved to psi
register find usage providers
moved to psi, register more services
javadoc fix