Coincontrol cleanup (e.g. add missing license)

- add missing license headers
- make compatible with Qt5
- enforce header cleanup style
- small code style cleanups
- rename Coin Control dialog into Coin Control Address Selection
- use default font for the windows labels (no monospace)

src/wallet.cpp

@@ -6,8 +6,8 @@
 #include "wallet.h"
 
 #include "base58.h"
-#include "net.h"
 #include "coincontrol.h"
+#include "net.h"
 
 #include <inttypes.h>
 #include <stdint.h>