Descent, now with Open Type Hierarchy

[Trass3r]

Also the hover feature/Open Declaration sometimes behaves incorrectly.
Unfortunately I couldn't really track down its cause yet :(

Usually when hovering over a function call the ddoc output is correct.
Then holding shift to see the source suddenly shows another function. F3 
also jumps to that false one then.

Sometimes Open Declaration makes eclipse get stuck (where sometimes that 
extra window "operation pending" or whatever it was reading is opened, 
sometimes not)