The compiler doesn't pass color to the parent process unless it is
called with `--colour on`. This commit adds those arguments to add
support for coloring in compiler outputs.
Runs a development server and auto-reloads when changes are detected to
files.
Note that a "change" is just an mtime update, Zig does a more
intelligent change detection so avoids unnecessary recompiles, so the
server reloads very quickly.