[TOUCH] Add tools for touch calibration in weston

This ports the set of tools for touchscreen calibration from seco-ne (Modular Vision 15-inch screen is inverted, needs a solution) and adds:

• tslib: provides packages for touchscreen calibration and tests
• touchcal-conv: helper scripts for conversion of different touch calibration formats into another
• weston.ini: a generic Weston config file with adjusted [libinput] configs

In short the procedure: user calls ts_calibrate utility for touchscreen calibration, after calibration the script converts the output into the udev rule for the touch driver. It will activate after reboot and stay persistent.

root@seco-genio700-e58:~# ts_calibrate

== Start touchscreen calibration ==

== Run ts_calibrate ==
xres = 1920, yres = 1080
Took 18 samples...
Top left : X =  205 Y = 7854
Took 11 samples...
Top right : X = 8001 Y = 7922
Took 10 samples...
Bot right : X = 7956 Y =  266
Took 12 samples...
Bot left : X =  256 Y =  354
Took 8 samples...
Center : X = 4154 Y = 3977
-6.798328 0.234883 0.000097
1067.465698 -0.000169 -0.129281
Calibration constants: -445535 15393 6 69957432 -11 -8472 65536

== Run post-calibration steps ==
cat: /sys/class/input/touchscreen0/device/capabilities/abs: No such file or directory
Written libinput udev rule to /etc/udev/rules.d/libinput-touchcalibration.rules

== Finished touchscreen calibration ==

Info: Please reboot the system to enable the new calibration across all services