Sugarbox v0.20

A quick version, to fix two problematic crashes.

Here's the log
- EDSK support secured : SCOOP #3 no longer result in a crash of the emulator. Also, if index table is in disorder, non longer crash the emulator
- Fixed of a memory bug in the SCP support : They no longer crash when leaving / ejecting the disk
- Fixed drag and drop of SNA files that wasn't working (and also corrected the  Snpashot  incorrect spelling)
- Improve the way vertical synchronisation is done by the monitor
- Adjust  Standard size  display to 384280 - Super cauldron or Prehistorik 2 now display correctly in full size