Thunderbird 60 support
This is the initial release with Thunderbird 60 support. Big thanks to @Skywalker-11 for doing most of the work here.
There is one important change to be aware of. The way you access the preferences dialog has changed. There is no longer a button in the Add-ons Manager. Instead, use the "hamburger" menu:
... or the application menu Tools > Add-on Preferences > KeeBird: