New examples

Here are the new examples that I wrote.
I don't like the non-blocking keyboard reading method that's used in some of these examples. Syscalls exist to achieve the same effect, and these custom routines should, in my opinion, only be used when one needs to know about multiple keys pressed at once (since none of the syscalls support it). I'm not sure that these routines work in the emulator*, which means that people using the emulator to test may think their code is broken.

* I'm sure that, at least some time ago, there were a handful of add-ins which wouldn't work properly, or needed source code changes, for the keys to work on the emulator.