SlewRate: add getter for current state without update

src/lib/slew_rate/SlewRate.hpp

@@ -63,6 +63,12 @@ public:
 	 */
 	void setForcedValue(const Type value) { _value = value; }
 
+	/**
+	 * Get value from last update of the slew rate
+	 * @return current value the slew rate is at
+	 */
+	Type getState() const { return _value; }
+
 	/**
 	 * Update slewrate
 	 * @param new_value desired new value