(It was set to NULL in the past to support the STA-architecture, but
 that backend is not maintained anymore)

They were used to selectively disable parts of the algorithm for
measurements in the paper. We now know that we always want them switched
on so remove the switches to simplify the code.

Because otherwise we confuse users with free_ir_graph vs.
remove_irp_irg. Change it so that free_ir_graph also removes the graph
from the irp list.

Make function definitions prototype declarations.

This should fix all cases of 64bit switches

noone was using it anyway

switch with double-word input leads to panic, but still better than
obscure verifier errors.

It was only a valid check in strongly typed unoptimized languages, not
much value in a firm-graph.