BTA mirror temperature network daemon
==================

Gather information from temperature sensors and send it over ethernet by network request like
hostname:4444/Tx
where x is 0 for upper sensors, 1 for lower and 2 for T measured by main controller.
hostname:4444/Tmean returns mean temperature

Answer format: "ID X Y T t", where

- ID is numerical sensor identificator (1st digit is controller number, 2nd digit - sensors' pair number and 3rd digit - number of sensor in pair)
- X and Y are cartesian coordinates relative to mirror center (decimeters),
- T is measured temperature (degrees Celsium),
- t is UNIX-time of last measurement.

To look graph over gnuplot utility collect gnuplot javascript files in subdirectory js of web-server
images storing directory, copy there script 'plot' and run service as

    netdaemon -g -s /path/to/web /path/to/log

Every 15 minutes it will calculate average values of thermal data and plot three graphs:
T0.html with top temperatures, T1.html with bottom and Tgrad.html with their differences (T0-T1).

** Signals 

SIGUSR1 - reread temperatures adjustment file

SIGUSR2 - dump to logfile all current temperature values and turn sensors off until next reading
