* get rid of printf
* use exceptions instead of error codes
* use Id_space instead of the individual block device registry
* use Cstring instead of char const*
* move method definitions > 1 line to .cc files
* rename Block Block_driver and Serial Serial_driver to avoid name clashes
with the Genode namespace and thereby simplify the code
* use lambdas for Block device lookup and apply
* switch to the Component framework
* don't use env(), config(), ... and hand over env to each connection
* use Attached_mmio and Attached_rom/ram_dataspace instead of manual
solutions
Fixes#2223
Merge the platform-specific files and classes (they merely aggregated
themselves) so that each platform provides merely one class
Sd_card::Driver. Also, the Sd_card::Driver_base class is introduced for
the generic parts of Sd_card::Driver.
Ref #2206
