Improve finite word length simulation

The following things should be supported:

• Provide both integer and fractional bits (one possibly being negative)
• Different quantization modes
• Support for complex values
• Set parameters in SFG GUIs simulation window

In addition, there should be

• Tests

added Completeness Enhancement Fast simulation Simulation labels

added SFG GUI label

changed the description

This is added in b_asic.quantization, but should be used in the simulation.

assigned to @ollha42 and @oscgu95

changed milestone to %Autumn version

added Finite word length label