Allow preventing trimming

[zemse]

I just found out that the spaces at the end of line are trimmed and there is no way to customise that.

textwrap/src/wrap.rs

Line 209 in 5db1066

lines.push(Cow::from(line.trim_end_matches(' ')));

Basically I want to preserve all the characters. I want to render a wrapped text in a TUI, and based on user interaction, I will know the char index on the wrapped line and then I need to be able to reach the same char in the original string. Currently since the spaces are always trimmed, it's non-trivial to do that.

[zemse]

Just noticed that this feature is already available on the master branch.

#587

Can you please publish?