Importing instruments over the tracker UI button assigns duplicate unit IDs

[LeStahL]

When exporting instruments over the "Save Instrument" button in the tracker and re-importing them using the "Load Instrument" button, the same unit IDs like in the instrument file are used for its units, regardless of whether or not those units already exist in the patch.

[vsariola]

Damn. Must fix soon, this is where they come from.

[vsariola]

Ok, I firstly assign IDs when loading an instrument and I also made a paranoid thing: always check for ID collisions and if they somehow happen, automatically fix them by giving a completely new ID to the later unit(s) having same ID as the first one.

[LeStahL]

super cool, thanks for looking into this so quickly! :)