cellSaveData* (cellSysutil) improvements

* cellSaveData improvements: cellSaveDataListLoad2 should work perfectly
(ignoring the fact that there is no dialog, and the first entry is
chosen automatically). cellSaveDataListSave2 has improved too. Some code
refactoring is required though.
* Reverted (deleted) Emu/SysCalls/Dialogs/ folder which I accidentally
included while merging Nekotekina's branch (including minor SaveData
changes).
* Modified some small things in cellGcmSys.