Refine definition of KiCad (#3743)

* Refine definition of KiCad language

* Add ".sch" as a registered Scheme extension

* Add more meaningful samples from real repositories

samples/KiCad Schematic/ultimate-temp-controller.sch

@@ -0,0 +1,69 @@
+EESchema Schematic File Version 2
+LIBS:power
+LIBS:device
+LIBS:transistors
+LIBS:conn
+LIBS:linear
+LIBS:regul
+LIBS:74xx
+LIBS:cmos4000
+LIBS:adc-dac
+LIBS:memory
+LIBS:xilinx
+LIBS:special
+LIBS:microcontrollers
+LIBS:dsp
+LIBS:microchip
+LIBS:analog_switches
+LIBS:motorola
+LIBS:texas
+LIBS:intel
+LIBS:audio
+LIBS:interface
+LIBS:digital-audio
+LIBS:philips
+LIBS:display
+LIBS:cypress
+LIBS:siliconi
+LIBS:opto
+LIBS:atmel
+LIBS:contrib
+LIBS:valves
+LIBS:relays
+LIBS:w_relay
+LIBS:ultimate-temp-controller-cache
+EELAYER 25 0
+EELAYER END
+$Descr A4 11693 8268
+encoding utf-8
+Sheet 1 2
+Title ""
+Date ""
+Rev ""
+Comp ""
+Comment1 ""
+Comment2 ""
+Comment3 ""
+Comment4 ""
+$EndDescr
+$Sheet
+S 1400 2100 2150 2000
+U 54E5B803
+F0 "controller" 60
+F1 "controller.sch" 60
+F2 "TC+" I L 1400 2300 60 
+F3 "TC-" I L 1400 2400 60 
+F4 "VCC" I L 1400 3750 60 
+F5 "GND" I L 1400 3900 60 
+F6 "RS485A" I R 3550 3700 60 
+F7 "RS485B" I R 3550 3800 60 
+F8 "DRAIN" O R 3550 3300 60 
+F9 "+5V" O R 3550 2250 60 
+F10 "SDA" B R 3550 2350 60 
+F11 "SCL" B R 3550 2450 60 
+F12 "GND" O R 3550 2550 60 
+F13 "RELAY_NO" I R 3550 2850 60 
+F14 "RELAY_COM" I R 3550 3050 60 
+F15 "RELAY_NC" I R 3550 2950 60 
+$EndSheet
+$EndSCHEMATC