Removed details for 'included view helpers' from the main view helpers page, since these each have their own page anyway (and these are linked to from the section above)
Added note about custom view helpers to the main view helpers page
Added link to URL helper page
Added individual view helper pages to contents page. Updated titles on these pages for consistency
Fixed formatting on HTML list and URL helper pages
Merge pull request #975 from tfountain/viewhelpers

View helpers page tidy up
Merge branch 'hotfix/975'

Close #975