and adjust the callers. discussed with and ok stsp@

spotted by noticing gotwebd crashing on some blame requests. Diff from stsp@ with a fix from tracey@, I'm committing it only because he is short on time. ok stsp@

Make the choice of diff algorithm configurable by diff API users. The got and gotweb programs keep using Patience diffs which are prettier than Myers. But tog should be as fast as possible since it is being used interactively. If performance of Patience diff gets improved later we can consider switching tog back over to it. ok tracey jamsek

ok tracey

Throwing this into the mix for a while, we can always get rid of it again if it becomes annoying. No objections from stsp@

thanks for all the help massaging this diff

ok tracey

Saves us from doing a malloc/free call for every item on the list. ok op@