Field (And quite frankly all member nodes) should store a reference to their DeclaringType
Changes to CExpr to make way for the new way of providing meta-data about an instruction (for validity checking)
Field expressions

Introduce FGet & FSet instruction generators
GetA,SetA expressions that generate get/set instructions for fields variables or parameters
Testbed: printing null should instead print a new line
Change Common compiler to support assigning to and reading from fields