Make SendEvent callable from all threads

This commit refactors the SendEvent call and moves it from the Input
ReaderBackend to to MsgThread. This allows all other types of threads
to access this functionality.

This necessitated a few more changes. Most importantly, one of the
ValueToVal methods was moved over to SerialTypes. Whereit arguably
belongs - there was nothing that was input-framework specific in
that method - and the functionality could come in useful in a number
of cases.

src/threading/Manager.h

@@ -88,6 +88,18 @@ public:
 	 */
 	void KillThreads();
 
+	/**
+	 * Allows threads to directly send Zeek events. The num_vals and vals must be
+	 * the same the named event expects. Takes ownership of threading::Value fields.
+	 *
+	 * @param thread Thread raising the event
+	 * @param name Name of event being raised
+	 * @param num_vals Number of values passed to the event
+	 * @param vals Values passed to the event
+	 * @returns True on success false on failure.
+	 */
+	bool SendEvent(MsgThread* thread, const std::string& name, const int num_vals, threading::Value* *vals) const;
+
 protected:
 	friend class BasicThread;
 	friend class MsgThread;