feat: duration formatting

[skokenes]

Changes

Adds:

• ability to format a duration when the # number tag is included
• ability to list durations in a terse format using # duration.terse

Fixes:

• if bad duration name is supplied, it is ignored and the default duration (seconds) is used

Cleanup:

• extracts duration functions into 1 place and exports them for re-use across both old and new renderer

Examples

Old renderer

New renderer