* use QOpenGLWidget instead of QGLWidget for ImageViewer
* use update() instead of updateGL()
* fix doSwapBuffers
* fix HexagonalColorWheel
* fix Viewer
* support AA_ShareOpenGLContexts & AA_EnableHighDpiScaling
* check Qt version
* Remove license support, and old editions
Previously, old code to support various editions of Toonz, as well as
license activiation code, was cluttering the repository.
Support for LINETEST is retained.
* fix conflicts
- using std::string;
- using std::wstring;
- using std::ostream;
- using std::istream;
- using std::iostream;
- using std::ostrstream;
- using std::istrstream;
- using std::fstream;
