Improve output of TextReporter

[piranna]

Three years ago I did some improvements of TextReporter allowing it to adjust better to terminals width and show more missing lines. Here I've done multiple improvements based on personal experience during this time:

• Trim whitespaces in missing lines column. This allow to don't affect report output if terminal gets resized, just only for the long lines
• split missing lines with whitespaces instead of commas. This improve legibility while not affecting number of visible missing lines
• show continuation dots for full ranges, not truncating any of them in half. This removes some info from missing lines column, but prevent confusions about the actual missing lines numbers.