I reorged labels on Cabal's GitHub

[Edward Z. Yang]

If you hate it I can change it back but give it a try for now.
If the "component" prefix in "component: solver" is too long we could go for
something like "C-solver" but I think that is less transparent.

I also added some new labels, "paging: ezyang (...)".  In the
parenthetical should be a quick summary of the types of things you are
interested in getting paged for.  I tried to guess some but I am
not perfect, please feel free to change your description / add a
label for yourself (I didn't get everyone) / tell me how you want
yours changed.

Edward