Handle long lines

[rase-]

For lines longer than 500 characters:

• Split line per match (and per 500 chars as window length) and do all the following steps for each:
  • Print line number (if not disabled)
  • Take some characters before and after the match (keeping a 500 char window length) as context
  • Add ... before the match if it is not within the first characters of the line
  • Strip colors if option given
  • Print individual match
  • Move the window

Before and after screenshots: https://cloudup.com/cM9D7mBIsyp