ecmascript: Handle plugin unload during URI route lookup
glw/eval: Rename (a,b) to (left, right) in glwf_assign to clarify what's going on
prop: Improve the 'Refusing to clean prop ...' error message

refs #2398
glw: Add (currently disabled) code to do proper unlink when using links for assignment

This is currently not needed but might be so in the future, so keep the code around

refs #2398