#236 added whitespace when using tags

[Joseph Andres Jr]

We have a scenario where in we convert HTML files (which uses htmlcleaner) to PDF. We noticed that if we for example try to use tag on a word then it adds whitespace before and after that word. For example "(Hello)" after PDF conversion it becomes "( Hello )". This behavior only happens when there is a character before and after the word but if there is an existing whitespace already then it does not add another whitespace, just preserves it.

[Joseph Andres Jr]

"<b>Hello</b>"

becomes

" **Hello** "

using PrettyHtmlSerialiser