rc-3

This is hopefully the last RC before 1.0 release.
Added COPR build support, the packages are here:
https://copr.fedorainfracloud.org/coprs/stsp/dosemu2/package/fdpp/
Below is the summary of few new additions:

• Confined (most of) freedos DOS memory writes. This is needed
  for the integration with some JIT engines, like the one in dosemu2.
  That JIT engine needs to be notified about the DOS memory writes.
• Support FILES= up to 256 (freedos only supports 128, then crashes)
• Fix "set volume serial number" fn for drive images/local drives
• Add support for COPR build system