Added BroadcastAdd and Reshape layer. Renamed Multiply layer to BroadcastMultiply. Added optional axis parameter to Softmax layer

added ReduceSum, ExpandDims and Multiply layer. fixed some problems with computeOutputTypes in Dot and Repeat layer

Implemented NetworkInstructionSymbol which is a parent of both UnrollInstructionSymbol and StreamInstructionSymbol. This is done so that we can keep track of the order of the individual instructions

changed UnrollSymbol to extend Scope rather than ArchitectureElementSymbol, thereby resolved error in EMADL

changed Unroll to be an instruction, like Streams. Still get errors when trying to access Unroll body from EMADL2CPP