Add Toggle Object Editability keybind

[mharis001]

When merged this pull request will:

• title, use case: sometimes you only want to edit a single object that is currently not editable and instead of going through the regular editable objects dialog with a small radius, this keybind provides a quick way to make the object editable (or not) by hovering over it
• Add updateEditableObjects objects common function
  • Replaces the old addObjects/removeObjects common events
  • Consolidates editable object updating in the code base to a single function

[ampersand38]

Works very well! I put my keybind as Alt + Right Click and am loving it.