Add a printer factory to simplify construction of printer drivers (#11)

Co-authored-by: Moritz Martinius <mm@cloudprinters.de>
Reviewed-on: #11

src/libusbwrap/interface/IUsbDevice.hpp

@@ -36,8 +36,7 @@ class IUsbDevice {
                               unsigned int timeout)  = 0;
 
     // getters
-    virtual const uint16_t getVid()        = 0;
-    virtual const uint16_t getPid()        = 0;
+    virtual const usbId getUsbId()         = 0;
     virtual const device::Speed getSpeed() = 0;
     virtual const uint8_t getBusNumber()   = 0;
     virtual const uint8_t getPortNumber()  = 0;