Weight metric fixes for diary notes

Fixes calendar entries (until someone changes their units). See https://github.com/GoldenCheetah/GoldenCheetah/issues/1067

Works around improper default labeling of metrics (i.e. weight in kg and not lbs even though the athlete is using imperial units) for now.

Also allows for building out of source (see https://github.com/GoldenCheetah/GoldenCheetah/issues/1180)