Refactor pqHelpWindow to get rid of the QWebKit qt dependency

Instead of using a QWebView widget, we simply use a QTextBrowser instead.

Change-Id: Ia92ed84dbd5bc07b927f9597f421835e10e677a7
Remove index tab in help window

Change-Id: Icb0bff168b590bf3c034fffbab7ac3d4bd43755f
Fix documentation style so it can be loaded correctly in the help widget

QTextBrowser only supports a subset of the css tags, so we need to be
careful with the one used.

Change-Id: I2560fab92c8049a195a878731ea848064d1568e8
Fix Query Data html file

Remove weird characther from the html file

Change-Id: Ic26559daf12815e44a988b30713dc5c24624675d
Merge topic '14720-RemoveQtWebkit' into next

6c8f5616 Fix Query Data html file
9966e6c9 Fix documentation style so it can be loaded correctly in the help widget
6bdaf2d5 Remove index tab in help window
22342165 Refactor pqHelpWindow to get rid of the QWebKit qt dependency