Doing away with __Trace.cpp and __Trace__Slow.cpp files

[gezalore]

Currently the trace functions are emitted in a separate pass primarilly because they are magic and EmitC adds a bit of extra text at the top of the trace functions. I would like to get rid of this and add any text necessary into the function bodies via AstText and friends so Emit does not need to know.

This would mean trace and implementation fucntions could be emitted by the same pass. The only question I have is whether we would like to keep the __Trace substring in the file names, or can we just put trace and implementation functions together ? Apart from reading the file names/build output, this makes no difference today at all. Fast/slow code would still be separate of course.

[gezalore]

I think it will not be too difficult/detrimental to keep the filenames, so I am closing this for now. might reopen if that thinking changes.