title: Regex - Amend lines and escape line breaks to match a specific tab-delimited pattern
body: <p>I have a supposedly 'tab-delimited' file with 4 columns contained in 5 million lines. The file currently looks like this:</p>
  
  <p><a href="https://i.stack.imgur.com/uiOfY.jpg" rel="nofollow"><img src="https://i.stack.imgur.com/uiOfY.jpg" alt="enter image description here"></a></p>
  
  <p>Tried selecting only the lines that started with a number but discovered that it did not help much as there were still some irregular lines which also started with numbers</p>
  
  <p>I am trying to clean up the file but I can't figure out a way of escaping the line breaks contained in the third column. The final output should be such that each line would contain four columns of tab-delimited text. Like this:  </p>
  
  <p><a href="https://i.stack.imgur.com/2bLrd.jpg" rel="nofollow"><img src="https://i.stack.imgur.com/2bLrd.jpg" alt="enter image description here"></a></p>