Conflict checker: 'conflicts with updated methods' menu in FileList
- check update# in fileIn
(- if update# is previous to any existing changesets in the image, warn that the conflict check won't work)
- if it's earlier than the current update in the image, then
- for each method in the fileIn:
	- check to see if the method exists in the image
	- if yes, check to see if the method exists in any changeset more recent than update#
	- if yes, flag it as a potential conflict

Possible merge tool: 'merge with updated methods' menu in FileList
- for each flagged method in the conflict checker,
	- lookup the original changeset for the method (latest numbered changeset which still precedes update#), and then get the original image method version from that
	- (lookup the latest updated changeset for the method and) get the latest image method version
	- merge the original->latest method diffs and original->fileIn method diffs into a new method version.