QtIFW

Split and implement new installer base, update checker.

Based on the former patches, split the installer base into its
own class. Use the new binary content read functions. Adjust uses
to match the new classes. Adjust installer base /update checker
signature and inheritance. Remove all now superfluous functions
from binary content. Core engine instantiates the operations now,
makes reading and writing more generic. Move product key check
into QInstaller namespace. Make use of the new command line parser.

Change-Id: I00aff79085b69ce627906881b43f374681ea7e91
Reviewed-by: Kai Koehne <kai.koehne@digia.com>