Integration of the TPI algorithm

Following the discussion here https://forum.hacf.fr/t/nouveau-thermostat-type-proportionnel-avec-gestion-des-presets-portes-et-fenetres-detection-de-mouvement-et-surconsommation/:

1. add the TPI algorithm

To use it:

1. edit your thermostat, (Integration / select your thermostat / configure),
2. choose the TPI function,
3. set an external temperature sensor id (mandatory),
4. configure the coef_c and coef_t or leave the default values (0.6 and 0.01) which seems to give good results.

This is beta release, don't hesitate to signal what seems to be wrong.

Enjoy,