ugtrain: fix headline per dynmem class

It is better to use "=" than "at" when showing the value of a
pointer to a dynamic memory object.
ugtrain: add 'game_path' config command

Now, we can specify an absolute path to the game. This is then used
to run the game and for 'objdump' in the discovery as well as in the
adaption scripts.
examples/README: add 'game_path' description