Use named parameters in get_timestamp() time formatting strings

[phw]

Summary

• This is a…
  • Bug fix
  • Feature addition
  • Refactoring
  • Minor / simple change (like a typo)
  • Other
• Describe this change in 1-2 sentences:

Problem

The function get_timestamp() in picard.util.time uses parametered strings like %.2dh %.2dm. For translation it is hard to see for what purpose those are being used for and how to replace them. Also order cannot be easily changed (should this be necessary in the target language), even though this is unlikely in this specific case.

Solution

Use named parameters like %(hours).2dh %(minutes).2dm

[rdswift]

This makes sense to me.

[zas]

LGTM