Be more explicit in assert of VariableLimiter

[ceraolo]

In Blocks.NonLinear.VariableLimiter, when limit1 becomes lower than limit2 an error is triggered.

Since these limits are dynamic, the user might not know what values caused the message, expecially in the case, that might occur, when this message is triggered at initialisation, and the tools do not show any variable value.

I propose to change the row.
assert(limit1 >= limit2, "Input signals are not consistent: limit1< limit2");
into:
assert(limit1 >= limit2, "Input signals are not consistent: limit1= "+String(limit1)+" < limit2= "+String(limit2));

The following screenshot shows how the output would be like in OM, if this change is done: