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Import emulators/advancescan

AdvanceSCAN is a command line rom manager for AdvanceMAME, AdvanceMESS and
any other MAME derivative.

The main features are:

 * Directly read, write zip archives without decompressing and
   recompressing them for the best performance.
 * Add, copy, move and rename files in the zip archives. Any rom that you
   have is placed automatically in the correct zip.
 * Recognize the text files added by rom sites and delete them.
 * Recognize the text files added by the rom dumpers and keep or delete
   them.
 * It's safe. On all the zip operations any file removed or overwritten
   is saved in the `rom_unknown' `sample_unknown' directories and kept
   for future uses. This will prevent any unwanted remove operation.
 * Generate differential rom sets.