dates: improve timezone handling
datestr:
- add format specifiers %1 and %2 for timezone hours and minutes
- remove timezone and timezone format options
- correctly find timezone hours and minutes for fractional and negative timezones
- update users
strdate:
- correctly find timezone hours and minutes for fractional and negative timezones
# should print nothing
# should fail
abort: path 'b/x' is inside repo 'b'
abort: path 'b/x' is inside repo 'b'
# should fail
abort: path 'b/x' is inside repo 'b'
# should arguably print nothing
# should fail
abort: path 'b/a' is inside repo 'b'