Add GPLv2 license text

Signed-off-by: Pavel Emelyanov <xemul@sacred.ru>
yoda: First more-or-less working example of code

There's an examples/ directory with yoda files. This version
of yoda can read it and generate .c + .h files with parser and
help text. Some keywords fro .yoda files are ignored, but what
it does can already be compiled ;)

Signed-off-by: Pavel Emelyanov <xemul@sacred.ru>