Moved keep-delete conflict resolution into MergeView.

Created originally on Bitbucket by ice-mmaclean (Matt MacLean)

Was already merged in Bitbucket before import, marked as merged by the import user

Instead of calling the UI from the HgResolveClient command, autoResolve will return false if there are any keep-delete conflicts.

The keep-delete conflicts will show up in the Mercurial Merge view, with different status' identifying them; Unresolved (Remote Deleted) and Unresolved (Local Deleted).

In the context menu for the conflict items, I've added an additional "Delete File" option to quickly review and delete keep-delete conflicts.

Marking a keep-delete conflict as resolved will simply remove it from the display, and keep the deleted file (same as previous behaviour)

I'm not sure passing the ConflictResolvingContext to the MergeView is the correct pattern or not. Please let me know if there is a better way.

Screenshot:

Also added a preference item, that when enabled will refresh the project of the hgRoot before a commit. This helps picking up newly added or modified files that were added or modified outside of eclipse.