mabla - new definition

This definition is more useful and matches `mabla`s usage. Also, Robin has already announced `mabla` and `zabna`'s new definitions official by fiat on the BPFK list[1] once, so this seems a mere formality.

Proposed definition: 
x1 is execrable/deplorable/wretched/shitty/awful/rotten/miserable/contemptible/crappy/inferior/low-quality in property x2 by standard x3; x1 stinks/sucks in aspect x2 according to x3.

[1]: https://groups.google.com/forum/#!topic/bpfk-list/rqMLDfmGBWk