Refactoring the bit addressing opcodes

[steveschnepp]

This refactors the bit accesses.

Again it gains in readability.

I moved every function in its own commit, as I had some bugs and elementary commits helped git bisecting, which was made neat with some rebase.

I let the fix commits in, as I learned about it and so can anyone reading the history via git blame. Those bool behavior are still a little arcane to me. Using them naively works perfectly, but casting them to int as 0 and 1 doesn't always.

I also fixed some minor timings

[steveschnepp]

Did you have time to review it?