Very prototypical SDL backend

[cra...@gmx.net]

Hello!

I've played around with SDL a bit, and created a basic prototype.

You can find the Merge Request here:
https://github.com/Interlisp/maiko/pull/403

If anyone could try this on windows and mac, that would be great.

Build the branch with cmake, something like the following:

mkdir build
cd build
cmake ..
make && PATH=.:$PATH ./lde ../../loadups/full.sysout

Right now, the resolution is hard-coded in src/sdl.c, key repeat doesn't
work, and the entire screen is bitblted every frame, so there's still
enough work left, but it might be good to investigate how well this
works in principle. Maybe this would solve some of the issues with X, or
maybe this will show that SDL is not the right backend to move to.

Thanks for any help with this,
Greetings, Peter