Should have been done earlier. 2.1.80 was burned in the pre-2.1.0->2.0.1
days, and we'd like to have odd subminor for 'working' and even subminor
numbers for pure cherry-picking release branches anyway.

- It's QML, not Qml. But this is only the file format.
- The umbrella term is Quick (or Qt Quick, to be sorted out)

Go to About Plugins and enable/disable plugins from there.

Reviewed-by: mae

The new QML Inspector depends on DebuggerPlugin. Also added a dropdown menu into
the debugger toolbar from which the user can select the used debugging
language, e.g. C++ or QML.