Recursive loops now seperate sfg property, fixed 0 input in Division and Reciprocal etc

• Added recursive loops as seperate sfg property.
• Changed so this property is used when calculating the iteration period bound for simpler code.
• Fixed 0 input in Division and Reciprocal.
• Fixed a bug where an operation going accross the schedling edge was not pipelined when recreating the SFG.
• Added a new example showing how scheduling is realted to pipelining/retiming.
• Updated scheduling ldlt matrix inversion tests by adding simulation check similar to how it was for IIR filters and FFTs.

Closes: #323 (closed) #236 (closed)