Things are getting super cereal...

Things are getting cereal...

Again, same thing as in zasm.

Same thing as in zasm.

It can only print a decimal literal. But still, that's a big step because
I hadn't implemented decimal formatting yet.

That's my mega-commit you've all been waiting for.

The code for the shell share more routines with userspace apps than with kernel
units, because, well, its behavior is that of a userspace app, not a device
driver.

This created a weird situation with libraries and jump tables. Some routine
belonging to the `kernel/` directory felt weird there.

And then comes `apps/basic`, which will likely share even more code with the
shell. I was seeing myself creating huge jump tables to reuse code from the
shell. It didn't feel right.

Moreover, we'll probably want basic-like apps to optionnally replace the shell.

So here I am with this huge change in the project structure. I didn't test all
recipes on hardware yet, I will do later. I might have broken some...

But now, the structure feels better and the line between what belongs to
`kernel` and what belongs to `apps` feels clearer.

Instead of expecting a `USER_CODE` symbol to be set, we expect `.org` to be
set in all userspace glue code. This gives us more flexibility with regards to
how we manage that.

Moreover, instead of making `USER_RAMSTART` mandatory, we make it default to
the end of the binary, which is adequate in a majority of cases.

Will be useful for my upcoming mega-commit... :)

Also important for upcoming mega commit...

Will be important for a mega-commit I'm preparing.

Most of register fiddling routines (which is now the only thing contained
in care.asm) are used by almost all userspace apps, often in inner loops.

That makes the penalty of using jump tables for those a bit too high.
Moreover, it burdens jump tables needlessly.

Because this unit is very small (now that string routines are out), it makes
sense to always include it in binaries.

Can possibly avoid a lot of debugging pain.

Also, make empty strings be parsed as invalid by parseDecimal.

And made them shorter in name. The new ascii.h file allow reuse in userspace
code.

Let's see where it will lead us...

Because scas isn't used as a reference anymore, no need to blacklist its bugs
anymore.

ref #41

There's a lot of looping through that table. At first, I wanted to add some
bisecting, but 16-bit additions and multiplications involved made the idea a
bit less appealing. I went with a very basic, hardcoded index which should
speed things quite a bit at a minimal complexity cost.

There was a little bit of cruft.

This allow a lot more characters to fit on that tiny screen...

ref #41

There's a couple of bit fiddling instructions that didn't have their
IX/IY variant implemented yet and without this commit, each of them
would have required a special routine. Not anymore.

We now require less special handling.

It was actually counted in 8-bit mode...

This reduces the need for special handling routine and will make my
life easier in my upcoming generic tratment of IX/IY prefix in upcodes

Giving I/O responsibility to spitUpcode gives us wiggle room for
upcoming refactorings.

That's a lot of code for such a small change, but there's a big difference
between 5 pixels and 4 pixels: 4 pixels requires compositing.

Also, fix visual glitch on line wrap.

ref #41

Previously, on real hardware (emulator behaved fine), we would routinely
get repeat keys unless pressing the button very fast. This commit solves that.

Previously, when being in A-Lock mode, activating Alpha wouldn't make
us go temporarily in digit mode, as is expected.