Summary

• Change the internal name of the Gateway 2000 Venus machine to all-lowercase for consistency;
• Bring some of the the machines that were added in the v4.1 branch line with the latest table changes on the master branch;
• Fix a string truncation warning net_eeprom_nmc93cxx.c;
• Fix a deprecation warning in the Qt UI code;
• Remove an #ifdef surrounding the entirety of midi_fluidsynth.c that was redundant and pointless.

Checklist

• Closes #xxx
• I have discussed this with core contributors already
• This pull request requires changes to the ROM set
  • I have opened a roms pull request - Rename the Gateway 2000 Venus directory to lowercase roms#214