Make context the first argument of operation objects
Add Paste operation to edit menu when opening the context menu on a blank area of the map (close#2508)
Consolidate localization behavior and init to a coreLocalizer function and singleton
Explicitly support `en-US` locale
Rename coreData to coreFileFetcher and export a singleton rather than using a property of coreContext
Add `apiConnections` property of coreContext to simplify adding a source switcher
Replace some init functions with re-callable, promise-supporting `ensureLoaded` functions
Make coreContext itself load the UI if a container has been specified at init time
Fix code tests
This is cleaner than adding hooks to transitionable actions, or performing validation
on every history change. We want validation to run after each operation, but not
while the user is drawing lines or typing in fields.
Trying to eliminate the minimum 10m distance for replacing the original
junction vertex - this is a small threshold. When _not_ replacing this
vertex, the unzorro code will wreck havok on a traffic circle.
(If there is no suitable vertex to use, it will snap to a point between
the nearest vertices, see #4146)
* Support move, rotate, reflect, delete post paste on multiselection
* Improve text and error msgs for singular vs multi selections
* Move `disabled` checks from actions to operations
* Reproject center of rotation (closes#3667)
* Cleanup tests
