Handling of whitespace at end of line

If you have an editor which strips whitespace at the end of the line when you save it. It will sometimes strip whitespace that is necessary for the test to pass. Ideally html2text should produce an output where the whitespace at the end should already be stripped.

a sample of tests where this occur:
- pad_table.md
- normal.md
- normal_escape_mod
- doc_with_table.md