Add test for complex mixed vector and class access

  Also correct missing switch entry for data initialization of a
vector class member.
Change coerce operations to have 2 arguments

  This allows move and coerce in the same operation.
Add extra spill offset argument operand_get

  This should force checking the spill offset and triggering logic
errors.
Do not change registers that may be spill/reloaded

  Changing them just before a save/reload will corrupt state.
Add a new test case with several operations and types

  Test is a basic Fibonacci and square operations.
Add debug output for expressions spill offset.
Correct regressions found in last test case.
Correct typo when splitting and merging patches.