FileSys/Kernel: Implement SetSize service call for File objects.
FileSys: split the constructor into an Open method, in order to notify the opener something went wrong.
Kernel: Return an invalid handle to OpenFile when it failed to open.
FileSys: Add static asserts for the Directory struct, and fix its fields position.
Common: Add a helper function to generate a 8.3 filename from a long one.
Core: Fix the SDMC Directory implementation to make blargSnes work.