Try.* functions

[sphaso]

PR #29 highlighted how there's a set of functions from Scala\Haskell that we haven't considered. In particular Try.map from Scala acts as a functor on Try objects, applying a function in case no exception was thrown.
Currently we have Either.try which maps a function application to an either, i.e., :ok if the function succeeded, :error if an exception was thrown.

A few questions from the top of my head:

• do we need Try.map when the user could use the with construct? (or just map after the Either.try)
• are there other functions outside of Either.try that we could implement?
• would it make sense to treat Try as a separate module (i.e. not piggybacking on either)?

@paolosimone @neslinesli93 @cottinisimone