Callers can now check whether reads fail, either by checking the return
value or by setting the buffer to a known bad value and seeing if it stays
untouched. I've added error checks to FileSystemGCWii and Boot_BS2Emu,
but not to Boot since it doesn't check any of its other reads either.

Limit size of loaded file systems

If a disc image is malformed in a specific way, Dolphin
will try to allocate a lot of memory, making it crash.
To avoid that, this change adds an artificial limit for
the size of file systems that Dolphin will try to load.

IFileSystem::GetBootDOLSize acts the same. The only difference is that it
reads the DOL offset on its own, but this change makes that optional.

Now that VS supports more printf specifiers, these aren't necessary

Filesystem: Return file list reference instead of modifying argument

Remove CFileSystemGCWii::Read32