Defer the absolute path check on argv[0] and log_init so that it becomes possible to run `gotd -n' to check the configuration file and get errors without specifying -d. Erorrs in the configuration now are actually always printed regardless of -d. While here also tweak an error message and print 'configuration OK' if -n ok stsp@

ok jamsek

This eliminates the previous performance cost by making 'got log -d' and tog diff view compute the diffstat while building the diff in a temp file like we do with 'got diff -d'. Also, keep the current 'got log -d' UI as per stsp's suggestion. ok stsp@

I failed to update regress when changing the diffstat summary line in the previous commit to use a singular noun after 1. ok op@ and stsp@