With this tool, we can send content to a TRS-80 directly to floppy.
This paves the way to writing ourselves a set of disks containing the
blkfs!

not actually tested yet...

Big bootstrapping change which greatly reduces the role of the modern
operating system in the bootstrapping process.

Also, fix some PSP leaks related to LOAD.

and remove cfspack, which will not ever be used again.

It makes the tool much more versatile. I'll have adev being included
in all recipes, so it can be assumed.

`xxd' is not available on all systems, and on others does not support
the `-i' flag. Since bin2c.sh relied on a tool that I can't seem to find
a compatible version of, I have included a simple, portable replacement in C.

Usage remains the same:
bin2c ARRAYNAME < inputfile > outputfile.

This change is also reflected in emul/Makefile.

To update LATEST offset more easily. Will be useful for recipes.

Sending the escape after its target made things complicated for upcoming
stuff I want to add. Although it makes `recv.asm` slightly larger, it's really
worth it.

It seems that my little "@.c" trick only worked in BSD make...

Some compilers don't like assigning stdout statically.

Use it in shell instead of using popen()

Also, removed leftover in runbin.c (what did it do there??) that
could result in tests falsely passing.

Things are now much simpler.

HL, instead of being preserved, is set to the character following
the last read character.

Also, make parseHexadecimal "tail" (HL). Soon, all routines in lib/parse
will do that, making the life of lib/expr easier.

Instead of going left and right, finding operators chars and replacing them
with nulls, we parse expressions in a more orderly manner, one chunk at a
time. I think it qualifies as "recursive descent", but I'm not sure.

This allows us to preserve the string we parse and should also make the
implementation of parens much easier.

For some reason, I've mistakenly disabled tests in test_expr without noticing
and I also broke "-123" parsing. Fixed.

This should make tests a bit more convenient to write and debug.

Moreover, begin de de-IX-ization of parseExpr. I have, in a local WIP, a
parseExpr implemented using a recursive descent algo, it passes all tests, but
it unfortunately assembles a faulty zasm. I have to find the expressions that
it doesn't parse properly.

But before I do that, I prefer to commit these significant improvements I've
been making to tests harness in parallel of this development.

This completes instruction support for the Blink tn45 example.