Rename "signature_data" to "operation_data"
Rename "signature_data" to "operation_data"

Old name (signature_data) was confusing, because this structure is already
used in encrypt and decrypt operation. Related functions are also renamed.

OpenSC/OpenSC,dengert/OpenSC,mouse07410/OpenSC,LudovicRousseau/OpenSC,metsma/OpenSC,LudovicRousseau/OpenSC,philipWendland/OpenSC,philipWendland/OpenSC,dengert/OpenSC,mouse07410/OpenSC,OpenSC/OpenSC,metsma/OpenSC,LudovicRousseau/OpenSC,philipWendland/OpenSC,dengert/OpenSC,metsma/OpenSC,OpenSC/OpenSC,mouse07410/OpenSC