additional optional parameter for getParamset: Array<String> values

[spali]

Add parameter Array<String> values to getParamset, to select which values should be returned of a paramset.

Currently to reduce the RPC calls, I always use getParamset to get the values. But on the cost of more bytes transferred over the network.
Allowing to define which values should be returned in a paramset would reduce the transferred bytes if required.
I suggest something the same solution as in getDeviceInfo, just an optional array parameter, to define some specific values.

suggested Signature:

Paramset getParamset(Integer peerID, Integer channel, String type, Array<String> values)