Dal#T issues

[stewSquared]

There are a few problems.

1. monadT should be in the implicit scope. We shouldn't be importing slickDal.monadT everywhere
2. T : Monad is too strong of a constraint. Applicative suffices.
3. The name T is often clashes and is not descriptive enough. Even if we're to keep a single letter name, F (for Functor) is more standard and semantic.

Feel free to add more to this thread. It should all be updated at once.

[jodersky]

1. monadT should be in the implicit scope. We shouldn't be importing slickDal.monadT everywhere

+1000 to this