Implement pattern matching

[WilliamRagstad]

There is currently a simple pattern matching system implemented, tho it does not support destructuring of lists or objects. Most advanced is the match expression which is just assigning a variable for each closure and checking if a condition is true, in that case that branch is taken and the value returned.
We need proper pattern matching as similar to Elixir for both assignment and match expressions.

Blocked by

• Add object types #14