Fix page search index

This change fixes some troubles in the search index:
- converts &nbsp; to spaces
- converts some others html entities to text
fix next_prev block bug that showed excluded pages in some cases

fix bug in next_prev block where last page in section gets returned even if it has the "exclude_nav" attribute.
Retain prev/next classes on disabled pagination links

Removing the prev/next classes on their respective pagination links when they are disabled makes styling them difficult as they then have the same specificity as the numbered (page 1,2,3) links. It's easier in CSS to target .prev.disabled than just .disabled, because the latter requires extra work to target the desired link since other links in the pagination might also have the .disabled class.
Use correct ADODB_FETCH_BOTH constant and remove spurious trailing x; to remove php warnings doing database backup.
added utility methods to the FileSet model

- $fileset->getFiles() returns an array of File objects for a given set
- two static functions to get the files directly via fsID or fsName
Runtime hash
Change the runtime constant
let wordSafeShortText point to shortenTextWord

both functions should lead to the same result so this code duplication should be removed.
Make date example a little more i18n-friendly

That way users can see month names in the current language.
fix bug if shortened strong is one single word
fixed invalid meta closing tag in DashboardBaseController
Make it so that if the active Captcha is removed it will go back to the default
using the api
updated new retrieval methods to call self instead of FileSet for best practice
updated getByID and getByName methods to be static
Change `private` to `protected` for Overrides

Change `private` to `protected` for overrides

- Change `$numThumbnails` to `protected`
- Change `$attributes` to `protected`
Let's mark Group::add as static
Add decodeEntities method to TextHelper
Merge pull request #979 from mlocati/patch-67

Fix page search index
Merge pull request #1042 from jordanlev/patch-22

fix next_prev block bug that showed excluded pages in some cases