Highlight qualified names based on last component (also highlight "XXX")

[maurges]

Previously qualified names were matched like

Map.insert
|  |  |
|  |  +- keyword
|  +- operator
+- type

Which is silly as those are not type nor operator! And I didn't like how it looked. Now such qualified names are matched as a whole.

The matching changed for HaskellType and HaskellOperator. I think HaskellKeyword need not be changed as that is only used where new keywords are defined, and you can't qualify in those places.

Also I added hightlighting for XXX like for TODO and FIXME since that is used in most other languages.