Bugfix code blocks start with an extra space

Paste SRC blocks into the start (not one space to the right) of the
temporary buffer used to highlight them (with pygments).
Fix validation errors

Thanks: http://validator.w3.org/unicorn/

- <a> tags don't have the 'alt' attribute
  - https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a#Attributes
- quote attribute values containing '=' characters
Add a post about shell stuff