Remove all uses of vm_absolute.
Remove vm_absolute.
Remove unused var.
Remove some functions that do nothing.
Reorder header.
Move line.
Add assert.
Simplify remove_shared_computation( ).
Remove some unused functions.
Remove some things we no longer need to #include.
Remove unused struct.
Stop including graph_register.H in context.H
Remove unused function.
Move function.
Move function decl.
Add new abs_ versions of computation accessors.
Add new function has_rel_computation( ).
Remove dup of rel_ computation accessors.
Rename rc to rc2.
Rename rel_ computation accessors.