fix(agents): correct implementations of SARSALambda and QLambda
fix(agents): correct implementations of SARSALambda and QLambda

- QLambda was not resetting the trace when an action was taken that did
not coincide with the target policy.
- QLambda and SARSALambda were not clearing the traces after a terminal
state was reached.

tspooner/rsrl