Converted Preorder and Poset to typeclasses
Added always/Given as a non boolean equivalent for oh/so
If "F" doesn't exist, :addproof checks "F.idr" as well

You can run Idris on F.idr with `idris F`, but then `:addproof` can't
find the file.
sinh, cosh, tanh

Inverses are left out because acosh and atanh aren't always real.
Fix scoping rules on lhs of with clause
Merge pull request #282 from JanBessai/DecidableOrder

Oh/So equivalent for Decidable and Preset, Poset as typeclasses
Merge pull request #283 from andy-morris/addproof

If "F" doesn't exist, :addproof checks "F.idr" as well
Merge pull request #284 from andy-morris/hyptrig

sinh, cosh, tanh