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* ZendPdf seems to be very picky about PDFs and is no longer maintained,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!
Yes, like you said.
I haven't checked whether the extractor service is Singleton but in any case the test of "function_exists" is very quick for PHP and does not decrease the performances.