Prevent exception on usage reports, file extension fallbacks

BUGFIXES

• If no URL to where a file is used can be generated during usage reporting, an empty string will be used. This fixes an issue where adding an image to a record on a page outside of a site or within a folder would throw an exception, for example when adding an image to a frontend user.
• Introduces configuration option qbankBrowserAllowed, a comma-separated list of file extensions similar to TYPO3 core's elementBrowserAllowed. If this option is not set, elementBrowserAllowed will be used. (See TCA Reference)
• Allowed image extensions falls back to the default image extensions ($GLOBALS['TYPO3_CONF_VARS']['GFX']['imagefile_ext']) if qbankBrowserAllowed or elementBrowserAllowed is not set.
• The "Use media from QBank" selector button is hidden if access token has not been set. This is instead of an exception.

Fixed version number

BUGFIXES

• In the initial release, the version number was not set in ext_emconf.php.

First release

FEATURES

• Select files from QBank DAM in a content element. A button is placed next to the "Add image" and "Select & upload files" buttons. Clicking the button opens the QBank file selector in a modal. Selected images are downloaded and the downloaded image will be reused if selected again.
• Usage reporting is submitted to QBank whenever an image is referenced on a page. (An Event Session Source ID must be set.)