Fix indentation of highlighted code
Add highlighting to first page of Ruby quickstart
Add syntax highlighting to 'about' page
Add missing newline in code snippet
Remove no-break space (U+00A0) from code examples

Replace no-break space (U+00A0) with normal space (U+0020) in
all code examples, because it can not be interpreted by Pygments
(when syntax highlighting is used), and is displayed with class="err".
Remove most of the no-break spaces

Remove all occurrences of no-break spaces (U+00A0)
except for the md5 sums on the 'downloads' page