Atomizer thread-safety and improvements

The atomizer library is now thread-safe. On top of that, more protection
checks have been added, code has been cleaned up and readings are better
also thanks to a new median filter. PWM clock has been increased to 144MHz
for additional precision in DC/DC control and feedback frequency has been
increased to 10kHz for higher slew rate.

include/Atomizer.h

@@ -27,10 +27,40 @@
 extern "C" {
 #endif
 
+/**
+ * Minimum output voltage, in mV.
+ */
+#define ATOMIZER_VOLTAGE_MIN 500
+/**
+ * Maximum output voltage, in mV.
+ */
+#define ATOMIZER_VOLTAGE_MAX 9000
+/**
+ * Maximum output current, in mA.
+ */
+#define ATOMIZER_CURRENT_MAX 25000
+/**
+ * Minimum output power, in mW.
+ */
+#define ATOMIZER_POWER_MIN 1000
+/**
+ * Maximum output power, in mW.
+ */
+#define ATOMIZER_POWER_MAX 75000
+/**
+ * Minimum resistance, in mOhm.
+ */
+#define ATOMIZER_RESISTANCE_MIN 50
+/**
+ * Maximum resistance, in mOhm.
+ */
+#define ATOMIZER_RESISTANCE_MAX 3500
+
 /**
  * Maximum output voltage, in millivolts.
+ * Deprecated: use ATOMIZER_VOLTAGE_MAX.
  */
-#define ATOMIZER_MAX_VOLTS 9000
+#define ATOMIZER_MAX_VOLTS ATOMIZER_VOLTAGE_MAX
 
 /**
  * Structure to hold atomizer info.