title: PHP Time Overlap check
body: <p>I need to check if two time ranges overlap.
  For example,</p>
  
  <p>time1: 13:20 - 13:40<br>
  time2: 14:00 - 14:30<br>
  time3: 13:30 - 13:50</p>
  
  <p>time1 and time3 overlap.  How do I check this?</p>
  
  <p>time1 and time2 have a gap of 20 minutes, but if the gap is less than 30 minutes it also should be considered overlapping.</p>
  
  <p>Anyone can help me with this, thanks very much.</p>