pass nBytes as parameter to GetMinFee(..)
Coin Control Features
[Qt] make most Windows appear centered on main GUI

- remove default value for parent variable in dialogs, which should appear
  centered over main GUI and pass appropriate value
- add some addition NULL pointer checks
Merge pull request #3255

309f796 [Qt] make most Windows appear centered on main GUI (Philip Kaufmann)
Merge pull request #3253

6a86c24 Coin Control Features (Cozz Lovan)
8dfd8c6 pass nBytes as parameter to GetMinFee(..) (Cozz Lovan)