addded State type.

Hi,

I added a go type for state, in case you are interested...

Btw: do you have any plans to add further plattform support? Windows seems doable, though not my main focus. Apple seems to have screwed up pcsclite to a degree  (or more precisely ships such an old pcsclite lib) that I'm baffled about how to support both libs with a single binding. (mainly: the osx version doesn't consistently use the typedefs from wintypes.h and cgo seems to be very strict concerning c-types.)

Cheers,
   -tim