Added CTCSS decoder in NFM RX

RSSI output is now pitch instead of PWM
Disabled RSSI output in WBFM mode

firmware/tools/fir_lpf.py

@@ -0,0 +1,20 @@
+import math
+
+m = 64 - 1
+ft = 300.0 / 24000.0
+
+taps = []
+window = []
+
+print("Normalized ft = " + str(ft))
+
+for n in range(0, 64):
+	taps.append(math.sin(2 * math.pi * ft * (n - (m / 2.0))) / (math.pi * (n - (m / 2.0))))
+
+for n in range(0, 64):
+	window.append(0.5 - 0.5 * math.cos(2 * math.pi * n / m))
+
+for n in range(0, 64):
+	taps[n] = int(taps[n] * window[n] * 32768)
+
+print(taps)