Hangup if you try and navigate away while editing an Edge

[jdanish]

Steps to reproduce:

Approach 1

1. Create node
2. Add edge
3. Change mind, cancel edge entry
4. Edge doesn't go away
5. Hit delete
6. Edge source/target blank now, but edge listing doesn't go away and stops other text fields from functioning.
7. Reloading makes the blank edge go away and now text fields are behaving the way the should.

Approach 2

1. • Click on a node
2. • Add new edge
3. • Cancel edge entry
4. • Ghost edge remains in the edge list
5. • ((editing is locked now, cant type in node search)
6. • Click create new node
7. • ((things unlock now))
8. • Cancel create node
9. • Ghost edge is gone now

[benloh]

This is related to #96

[benloh]

Fixed with 2577488

Canceling a new unsaved edge now properly removes the new edge component and restores the node editor state and search field state.