Sub-minute syntax

[g105b]

This is non-standard, but it would be nice to be able to schedule a script for every 10 seconds. At the moment, * * * * * is equal to once per minute, which is currently the most frequent cron setting.

Setting */10 * * * * will trigger every 10 minutes.

My proposed syntax for every 10 seconds:

*:10 * * * *

The colon is obviously different than the slash, and is already used in time formats, so it shouldn't be too difficult to understand what this does without reading the docs.

[g105b]

It might be worth dropping the 3rd party dependency to dragonmantank/cron-expression seeing as this will be non-standard now.