fix Argument class name typo
Improved handling of dos/windows arguments greatly.
Merge pull request #110 from krockode/patch-1

docstring typo fix
Fixed underline
Added click.pause
Added a new item to the why list
Changed upgrade note to be more correct.
Moved textwrap functions into a delayed import to speed up execution time if help is not needed.
Add test to ensure click does not import too much
Added pypy to travis