Demo: Memory Operations

Two demos for part 02, on what a program can do with memory and what stops it.

Demo	What it shows
basic-memory-operations/	The five operations in twelve lines -- allocate, write, read, execute, free -- and the one that faults.
memory-access/	The same accesses against the areas a program already has: read and write data, read and execute code, and three ways to crash.

The first shows that execute is a permission like any other; the second shows that every area has its own set.