Midi saving hotfixes

Hey guys, just to let you know but if you upgraded to the previous version of KobiMusic a few days ago, you probably want to upgrade to this version, since the previous version includes some critical bugs, and you may risk losing your generation due to an issue in the midi saving process. Along with patching that issue, this also fixes a bug that @Charem and @MayroSMM has pointed out, which was an issue where saving a midi with drums would play as a piano track for some software. A few other tweaks were added into the midi export system as well: exporting instrument sets from the software, and the tempo being updated to the playback speed.