Bug 419098

SUMMARY
Currently, the remove training spaces has 3 options and it works quite well in general. However, nowdays, people use Markdown or Asciidoc to write their documentation and save it in various platforms like Gitlab, or Github. 

Line break in MD is entered when there are 2 spaces at the end of the line. 
However, we usually want to have the "Remove Trailing spaces" option enabled. 

Ideally, we would like to have an exception for specific file types, so when we select the "Remove Trailing Spaces" (either the whole document or modified lines only), we can select for which file types we don't want it.