Also add more games to the list of optimizations being enabled by default.
This will bring Pillars of Eternity down to around ~2 GiB shared memory,
which is still too much but without implementing another workaround that
adds a prefix filter I cannot really fix this. Certainly better than 24...
Some games are using the installation directory to store savegames.
To avoid deleting those, only remove files that are actually in the
manifest and only delete the directory if it is empty.
Seems to be a variation on CRC-64-ECMA.
This python version is of course very slow.
That should not be a big issue however, since
it is only required for serialising rather
small save game data.
Eventually the "download" command will be changed to
set the --no-install flag by default and "update" will
become --update-only. For now remain backwards compatible
to give people a chance to adjust their scripts and habits.
Fixes#18
In the future we might extend this with other features,
such as specific post-install things that some games
may require to work or preconfigured WINE settings.