cfgparser: make the dynmem file path configurable

On the Nokia N9 MeeGo 1.2 Harmattan phone we don't have enough
space in /tmp (only 4 MiB). So the dynmem file path must be
configurable. Example for that phone:

dynmemfile /home/user/MyDocs/Documents/dynmem_file.txt
cfgparser: add config option to disable preloading

On the MeeGo 1.2 Harmattan platform the regular user is not allowed
to use LD_PRELOAD. So the idea is to patch the ELF binaries with
patchelf to inject the library libmemdisc or libmemhack. In this
case the command line option '-P -' or the config option 'no_preload'
is required. The behaviour is the same but LD_PRELOAD isn't set.
ugtrain: run_game: support loaders which fork

If a loader like 'xdg-open' is used to fork the game process, we
can't use the waitpid() method to wait for the game process. We have
to handle that as if the game has been running already before.