PR 32097

Added image and pdf extraction.

Facts and todos:

* Need to add TCA definitions
* This uses PHP functions only, no support for third party tools
* This extracts the most common exif and ipct data from images
* Currently no support for XMP data
* Think about normalizing city and country codes by using static_* data
* ZendPdf seems to be very picky about PDFs and is no longer maintained,
	but I  found no good alternative (except pdfpasrer but its about 30mb)

We could squash some commits to have a nicer merge late ron. Please give some feedback!
I would implement that as protected method:

	/**
	 * Tell whether the PHP EXIF extension is available. 
	 * 
	 * @return bool
	 */
	protected function isExifExtensionAvailable(){
		return function_exists('exif_imagetype') && function_exists('exif_read_data'); 
	}