Macro preprocessor added

[Bill E]

It does 2 things, check for common errors and fix some, and adds some new features. The output is compatible with macro and macro1.

Here's the documentation, it's checked into my repo, https://github.com/wjenh/pidp1-mods.git, in the Tools/M1PP directory, with the documentation in the Docs directory.

[Bill E]

I added another check, flexo pseudo-instruction  is broken for mixed-case characters.

Why? Concise code uses shift characters. If you do something like flex Abc, what you get is 'upper A lower'. Any mixed case use isn't likely to do what you expected.

Any all-upper use might, but only if you do flexo A or flexo AB, to leave room for the shift character.

Interestingly, the char pseudo-instruction does handle this by not allowing shifted characters, not totally useful but at least safe.

Repo updated.

Bill