Removed unnecessary mli file
Added indirect ast constructor

Most locations are still unhandled
Also made base_of (from the typechecker) be consistent with other
similar functions, making exception threading simpler.
Added basic indirection to the interpreter
Added indirection handling to necessary places

Also removed warnings from the code so it's nice and clean
Added small tpch3 query

A smaller dataset means that we can actually finish it in time with the
interpreter. Also tried to fix some values so we get something other
than 0s.