* Add files via upload

* a monolithic build recipe for ZX Spectrum

* emulation and emulated tapes in README.md

You'll see where I'm going with this...

All of that should help me implement sdc support much faster in
Forth.

I now get to "fls" in recipes/rc2014/sdcard!

so far, it goes through initialization with the rc2014/sdcard recipe.

`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.

It was badly handled.

All "stop pings" are now explicitly made at appropriate places. This
fixes a problem I've introduced in the last commit where RAM+ was
unexpectedly part of a stable ABI because of "HERE" usage in dummy.fs.

This system will, anyways, soon change because boot.bin and z80c.bin
will be built during the same process (but there's a bit of retooling
to do before I get there).

Doing this was a bit stupid. These offsets are constants. Moreover,
having them in stable ABI had us construct the boot binary from the
stable ABI of the host, making it very difficult to change RAMSTART
for a new system.

This commit cuts Forth's dependency on zasm. It now self-assembles
its own boot-binary! Things are a bit messy now, I'll clean up
later.

Make LATEST configurable through a value in the binary instead of through
a ZASM constant. This enables the simple concatenation of compiled dicts and
simplifies the build process.

Not needed anymore. CONSTANT does the trick.

Now we're having a real nice and tidy forth.asm...

We refer to stable offset as direct numbers instead of offset to JTBL.
Simpler that way.

forth.asm under 1K lines!

inc (hl) is 8 bit, inc (hl) is 8 bit, inc (hl) is 8 bit. Now I hope
I'll remember...