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)
Merge pull request #3267

0689f46 Coincontrol cleanup (e.g. add missing license) (Philip Kaufmann)