store some user settings outside project file

[binary1230]

Actually collaborating with someone on a project now, realizing a few things about the save file format:

In the actual save format (.dizraw or .diz), we're storing a few things:

1. the path to the ROM AttachedRomFilename
2. the filename of the ROM AttachedRomFilename
3. and the hash of the ROM InternalCheckSum
4. the current offset of the main table (so it saves your last place you were looking at) CurrentViewOffset

Of all that, we should probably ONLY store the hash InternalCheckSum in the project file, and save the other settings in the user-specific settings area (the DefaultSettings area). Otherwise when multiple people are collaborating, these settings are always going to be flapping in the XML diff of the save file.