test, add regression cases for dseq with empty ranges (adapt old tests too)
fix, properly check for range validity in __in_range_p() predicate
cosmetics, declare and define temporary vars as scope-tight as possible
Merge branch 'bug/dseq-invalid-range'

* bug/dseq-invalid-range:
  cosmetics, declare and define temporary vars as scope-tight as possible
  fix, properly check for range validity in __in_range_p() predicate
  test, add regression cases for dseq with empty ranges (adapt old tests too)
test, provide regression case for dconv in strict mode
minor, also clamp business days to max value in __guess_dtyp()
minor, introduce fix flag to keep track of fixups during date parsing
test, adapt regression to actual fix (coming in the next patch)
minor, capture the fix flag and propagate error code 2 (unless there's -q|--quiet)
test, adapt dconv tests to new error handling
minor, only interpret integers as time when there's at least the hour AND the minute
Merge branch 'feat/strict-date-reader'

* feat/strict-date-reader:
  test, adapt dconv tests to new error handling
  minor, capture the fix flag and propagate error code 2 (unless there's -q|--quiet)
  test, adapt regression to actual fix (coming in the next patch)
  minor, introduce fix flag to keep track of fixups during date parsing
  minor, also clamp business days to max value in __guess_dtyp()
  test, provide regression case for dconv in strict mode
Merge branch 'feat/read-time-only-with-hour-and-minute'

* feat/read-time-only-with-hour-and-minute:
  minor, only interpret integers as time when there's at least the hour AND the minute
minor, adapt dround to new error propagation on fixed-up and invalid values
test, provide regression cases for error propagation in dround(1)
chore, follow-up, document return code behaviour for dround(1)
minor, adapt dseq to new error propagation on fixed-up and invalid values
minor, adapt ddiff to new error propagation on fixed-up and invalid values
test, adapt ddiff regressions to error propagation
minor, adapt dadd(1) to new error propagation on fixed-up and invalid values