Removes all the extra whitespaces at end of lines,
inside tags, and removes extra newlines

To clarify what's meant by "from a logical perspective" here, I
consulted Python's PEP8 style guide, which provides some helpfully
precise language: 

> Extra blank lines may be used (sparingly) to separate groups of 
> related functions. Blank lines may be omitted between a bunch of 
> related one-liners (e.g. a set of dummy implementations).

https://www.python.org/dev/peps/pep-0008/#blank-lines

I adapted this passage to the existing language for the newline rule.