Add Alternative

[JorgeCastilloPrz]

Fixes #249

This one is very simple. Just added Alternative typeclass with no methods (since the only one it contains is the composed one and it's defined as an extension function on the Composed file.

Wanted to write WriterT instance for Alternative but was not possible due to WriterT over constraints, since it's asking for a Monad and not a Functor.

MonadCombine almost all the instances for Alternative, so will be done in a different PR.

[codecov-io]

Codecov Report

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The diff coverage is 0%.

@@            Coverage Diff            @@
##             master     #256   +/-   ##
=========================================
  Coverage          ?   49.98%           
  Complexity        ?      247           
=========================================
  Files             ?      114           
  Lines             ?     2563           
  Branches          ?      293           
=========================================
  Hits              ?     1281           
  Misses            ?     1167           
  Partials          ?      115

Impacted Files	Coverage Δ	Complexity Δ
.../main/kotlin/kategory/instances/StateTInstances.kt	87.5% <ø> (ø)	0 <0> (?)
...y/src/main/kotlin/kategory/typeclasses/Composed.kt	67.64% <0%> (ø)	0 <0> (?)

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