New Event Selector (#404)
* Replaced the JButton options on the object frame's event tree with a toolbar at the top. It uses icons, tooltips, and shares the same Swing actions as the tree's context menu. This includes breaking "Modify" back up into 3 separate options for Josh including Add/Replace/Duplicate.
* Extracted the Drag and Drop action group label helper to a utility method so it can be used in other places.
* Used the line-through label utility method to decorate the action list, object frame event tree, and timeline frame moment list.
* Removed the "Dock Event Tree" preference and associated references to it.
* Designed the event selector from Josh's mockup in place of the existing one. This includes using the label utility method I mentioned above to caption the new event selector options.
* Fixed some alignment issues with the object window selector on the event selector. I changed the alignment to baseline and used a shorter, yet more descriptive label.
* Used private-by-default for most of the new event selector stuff and retroactively changed some things to private.
* Deleted old code by me related to the event panel that's no longer relevant.
* Fixed the toggle button on LGM's main toolbar so it is correctly synchronized with the visibility state of the new event selector dialog.
* Added 32px * 32px versions of the event icons exported from the Calico light and dark SVG. Also added the 18px * 18px plus icon used for adding stuff to lists/etc.
* Added missing localization tag comments to nearby code. This includes places I forgot to originally, like for the "Physics" properties of an object.
* Decoupled the object frame from the event selector by having the event selector tell the object frame the function it uses when you add/replace/duplicate. This is opposed to how we were having the object frame ask the event selector (since the event selector has been made private).
* Fixed up several of the translations which had missing keys, extraneous colons, mistakes, formatting mistakes, and cruft. Provided translations for new keys was obtained from Google Translate.