Add CPU Max temperature constraint

[AndySchroder]

In addition to target load, it would be really cool to see limiters for Max CPU temperature. Why would this be interesting? Well, when a CPU gets really cold, it can become erratic and crash the entire system. Rather than build a special thermostatically heated enclosure for the computer for the winter (which then becomes something you need to cool in the summer), just generate some load until a Max CPU temperature is reached, then slow down the load generation. That Max CPU temperature is then actually your target Minimum CPU operating temperature. If ambient air temperature gets above the Max CPU temperature, extra load generated should drop to 0. If Ambient temperature goes far below the Max CPU temperature, load will increase until the target extra load generated is achieved. This way, some spare CPU resources will still be available instantaneously, and if needed continuously, extra CPU load generated will drop to 0 as the real system demand is non-zero for a period of time.

[GaetanoCarlucci]

This is an interesting point! It can be a nice project for a thesis :-)