added isSet() method to Input<T> to replace bool conversion operator
bugfix: Input<T> did not send InputSet signal if assigned to non-initialized output
added getSharedPointer() to Input<T>
create shared pointers to Input in Inputs
bugfix: SimpleProcessNode needs check for != 0 before locking input
changed to new exception macro
fixed compile errors in ProcessNode.cpp
bugfix: Input should not send InputSet<T> when the pointer of the assigned output changed
bugfix: SimpleProcessNode: not being set to non-null pointer does not imply input was not assigned