imitone 0.13.0a — tiny bugfixes

This is a tiny bugfix update to address a few crash reports we saw over the weekend.  Thanks for hitting that "send to imitone HQ" button — we actually read those, you know!

App fixes:

• Prevent 'mainOutputToggle' crash when closing while playing sound.
• Prevent 'selectedVoiceChanged' crash when manipulating audio setup.
• Prevent 'service_not_found' crash with defunct key combo shift-M.
• Corrected the app's minimum Mac OS X version to 10.12 in its metadata.

Caterpillar Photo (Antheraea yamamai) by Harald Süpfle, used under CC-BY-SA.