Sc6.sc3.vstreams subscribing to several streams

created a virtual stream process module that can subscribe to arbitrary many streams and/or virtual streams and apply any of the predefined functions in vs_func_lib module
Short description:
    1. Gets the latest value for each stream it is subscribing to (internal history)
    2. Wait for a new data point from any of the streams
    3. Update the internal history
    4. Calculate the value using a predef. function and set a new timestamp (including ms)
    5. Stores new data point in ES and then publishes it to RabbitMQ.
    6. Back to step 2 unless it receives atom: quit