refactor(ExpressionFusor): Break out visitors into their own namespace
refactor(ExpressionFusor): Break out exception into its own file
feat: Add true partial expression application functionality

This feature allows for users to partially apply an expression fairly
simply and, due to metaprogramming, with appropriate compile-time errors
and Intellisense hints.
chore: Add changelog for 0.2.0
chore(release): Bump version number and update release notes in nuspec