use new VDR interface for CamSlot decrypting

Changes was introduced in VDR 2.1.3
drop unnecessary code
DeCSA: remove stall checks and all kind of waiting
added adapter_index to socket messages

The plugin is using a single global connection to camd.socket.
In this case it was unable to distinguish between adapters
when receiving CA_SET_PID and CA_SET_DESCR.
A conflict was occurring when a PID numbers was the same across
adapters (even if it uses different descrambler indexes).
Now the PIDs are assigned per adapter, avoiding simultaneous
channel decryption problems.

An adapter_index byte was introduced in OSCam rev9095.
SCCAMSlot: rename Reset() to ResetSlot()

This rename is needed to avoid name conflict after making
VDR's cCamSlot::Reset(void) a virtual function.
Override ProvidesCa() and stop scanning channels.conf for CAIDs

The changes in VDR let us override ProvidesCa(const int *CaSystemIds)
informing VDR that every CAID can be decrypted by our CamSlot.
Of course it depends on OSCam but we don't know it at this stage.
Drop the old code which generates a list of CAIDS from channels.conf.

Closes #39
Delete unused defines and variables