Fixed lvalue-store
Added op-via-memory back in
Don't get the lvalue-version if loading address
lvalue logic is handled by the AST, not the backend
Removed assert in v_to_mem_given
Changed flow control in out_op() - one exit
va_arg() sets lvalue appropriately for updating va_list:s
Changed backend types to include distinct lvalues
Added lvalue-to-rvalue casts
lvalue to rvalue example