request confirmation when navigating away from an unsaved entry
This PR implements changes required to address #62 (closed).
- 44fd4002 adds support for tracking the "modified" state of the current draft entry
- 7f0931f2 resets the modified state on successful save
- 612afbb7 adds a new component which monitors the "modified" flag and prevents navigation from in-process entries
Closes #62 (closed).