Fix examples

If there is no namespace declared in the example, the backslash before the class name is not necessary and can be confusing
Use language independent permalinks for php.net urls

@see http://php.net/urlhowto.php
Add paragraphs about two global usergroups
Merge pull request #496 from jrfnl/Global-usergroups

Add paragraphs about two global usergroups
Merge pull request #492 from jrfnl/Use-php-net-permalinks

Use language independent permalinks for php.net urls
Merge pull request #493 from jrfnl/Adjust-examples

Adjust examples
Fix line wrapping consistency - round 1

Comply with the 'wrap at 120 chars' style rule stated in the contributing.md document
Verify link consistency - round 1

- Verify that all named links at the bottom of a post are in use, otherwise either remove or add link in post
- if the post uses named links, try and make sure all links in the post are in that style
- ensure logical order for the named links at the bottom
Spacing
Jekyll header spacing consistency
Wrap bullet list
Style consistency Round 2

- spacing of jekyll tags at top of file
- line wrap at 120 chars
- url/link verification and move to bottom and order
Minor style fixes

- use `()` when referencing functions