Fixes several files incorrectly stated a different license from the actual project, as well as the copyright headers included in all files. This change has no effect on the licensing terms, it should clear up a bit of confusion by contributors. Plus the files get a bit smaller, and we have less duplicated information across the entire project.
Overall the project is GPLv2 if not built with Qt, and GPLv3 if it is built with Qt. There are no parts licensed under a different license, all have been adapted from other compatible licenses into GPLv2 or GPLv3.
While the long descriptions were useful, keeping the updated and translated is pretty much impossible. Technology moves fast and not everyone that translates the project knows a lot about technology.
Therefore the long descriptions have now been replaced with a button that opens the wiki page for the feature instead. This should drastically reduce the number of help cases, and improve the translation coverage at the same time.
Changes applied:
* Moved utility files to /util/.
* Removed unused #includes.
* Removed unused ::ffmpeg::tools function.
* Removed unused variables.
* Fixed missing parentheses in the version macro.
* Fixed missing override on virtual function overrides and removed unnecessary virtual keyword from them.
* Disabled additional warning for ATL headers on MSVC only.
* Replaced direct printf parameters with their macro equivalent.
* Replaced C-style casts with C++-style casts.
* Applied clang-format again after an earlier change to the CMake file broke the integration for it.
