fixes #3 by trimming beginning and trailing whitespace in cell content

[NogsMPLS]

[NogsMPLS]

Actually fixes #3, lol, typo'd the commit message.

[laurent22]

That wouldn't fix it if the new lines are inside the cell content though. In my opinion, the cell content should simply go through content.replace(/\n+/g, "<br>") which will renders correctly in most Markdown renderers, and will also allow having new lines inside table cells.