add 555 timer adjustable duty cycle example circuit

src/com/lushprojects/circuitjs1/public/circuits/555dutycycle.txt

@@ -0,0 +1,21 @@
+$ 1 5.0000000000000004e-8 7.010541234668786 69 10 50 5e-11
+165 224 144 272 144 4 4.999954555803549
+w 192 240 224 240 0
+w 192 240 192 272 0
+w 192 272 224 272 0
+c 192 384 192 432 4 2.5e-10 2.447660113598445 0.001 0
+g 192 432 192 448 0 0
+d 352 352 304 352 2 default
+w 352 208 352 352 0
+R 288 112 288 80 0 0 40 5 0 0 0.5
+O 352 208 416 208 0 0
+g 320 304 320 320 0 0
+w 288 112 352 112 0
+w 352 112 352 176 0
+174 304 416 272 368 1 100000 0.5 Resistance
+d 304 416 352 416 2 default
+w 352 416 352 352 0
+w 272 384 192 384 0
+w 192 384 192 272 0
+o 4 2 0 4099 10 0.000390625 0 2 4 3
+o 9 2 0 36874 10 0.00009765625 1 1

src/com/lushprojects/circuitjs1/public/setuplist.txt

@@ -230,6 +230,7 @@ crystalosc.txt CMOS Crystal Oscillator
 -
 +555 Timer Chip
 555square.txt Square Wave Generator
+555dutycycle.txt Adjustable Duty Cycle
 555int.txt Internals
 555saw.txt Sawtooth Oscillator
 555lowduty.txt Low-duty-cycle Oscillator