PL/PDF v4.6 emergency release

With the latest, 10.2 iOS release most PDF files seemed like they were blank, however in reality they weren't. We looked into what may cause the error and we came to a solution.

PDF uses deflate co mpress for stream (example page content) object, this method contains 4 bytes Adler32 checksum. PDF readers (Acrobat, Foxit and prev iOS) do not check the Adler32, which means PDF producers usually do not calculate Adler32 (for example we use '00000000') or checksum calculation is incorrect.

Now that in iOS 10.2 the system checks the Adler32 we added it to the stream, therefore the blank PDF files are fixed on the new iOS release with PL/PDF v4.6.