Match time in mm:ss, or hh:mm:ss if `hh > 00`
Matches time strings formatted as mm:ss or hh:mm:ss under the following conditions:
mm:ss**: only if mm and ss are less than 60
hh:mm:ss**: the above condition applies, but it selects hours only if hh is greater than 00
Submitted by Liddack - 6 years ago