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/qt/sendcoinsentry.cpp

@@ -27,7 +27,6 @@ SendCoinsEntry::SendCoinsEntry(QWidget *parent) :
     ui->payToLayout->setSpacing(4);
 #endif
 #if QT_VERSION >= 0x040700
-    /* Do not move this to the XML file, Qt before 4.7 will choke on it */
     ui->addAsLabel->setPlaceholderText(tr("Enter a label for this address to add it to your address book"));
     ui->payTo->setPlaceholderText(tr("Enter a Bitcoin address (e.g. 1NS17iag9jJgTHD1VXjvLCEnZuQ3rJDE9L)"));
 #endif