fix: 3s Buffer compute max EM PLoss for FL OPs

In case of issue #848, max load could be achieved only 2 seconds instead of 3 seconds as required by regulation (EU) 2017/2400:

• The ContinuousTorque OP which is used to compute the 3 sec. buffer is not the most difficult one to achieve
• A lowest speed OP presents a higher loss, and remaining at this OP empties the buffer faster -> All points of the FullLoadCurve are introduced in the computation of the 3 seconds buffer, and the max value for the buffer is selected.