QT_NO_KEYWORDS prevents Qt from defining the `foreach`, `signals`,
`slots` and `emit` macros.
Avoid overlap between Qt macros and boost - for example #undef hackiness
in #6421.
- try to enforce the same style to all Qt related files
- remove unneeded includes from the files
- add missing Q_OBJECT, QT_BEGIN_NAMESPACE / QT_END_NAMESPACE
- prepares for a pull-req to include Qt5 compatibility
