Improvements to tooltips, copy-paste, and shortcuts

Fixes and improvements

• Tweaked bezier length/angle tooltip location when adjusting vertices.

• Copy-paste shortcuts in the file browser are working again.

• Fixed issue with copy-pasting artboards with nested artboards.

• Resolved crash when dragging out guides when a file has no artboards.

• Updates to copy-pasting child bones.

• Fixed recent issue with period/dot key not working in timeline fields (e.g., Speed).

• macOS app: In fullscreen the Cmd+period shortcut moves the playhead to the next key as expected.

• Windows app: Fixed Alt key shortcuts.