Add H.pad
Add H.format_log_datetime
Use H.format_log_datetime
Merge branch 'refine-log-datetime-format'

Close gh-129.
Simplify generating excerpts for random supplies
Separate H.excerpt_from_sid
Remove an intermediate variable on rsid
Remove an intermediate variable on (shared_)at
Define excerpts for predefined supplies
Merge branch 'refine-excerpts-for-predefined-supplies'

Close gh-131.