Log Message:
libspectrum: update to 1.4.1

libspectrum 1.4.1:
* Fix generation of malformed RZXs
* Various minor bug fixes/improvements:
  * Build test program on "make check" rule
  * Additional unit tests for SZX reading/writing
  * Free DivIDE/DivMMC memory from snapshots
  * Remove C99 typedef redefinition of libspectrum_mmc_card
  * Correct version for MLT class addition