[Interfaces] Added IDataFilterCallback_f.
[Imgaste] A little bit cleaner code.
[Imgaste] Support IDataFilter callbacks.
[Interfaces] Clarified IDataFilter docs.
[Imgaste] We were probably leaking replies.

Blind-writing this, need to test.
[CpuLoad] Added Linux backend stubs.
[CL] Moved structures to structures.
[CL] Fixed a typo.
[CL] Proper /cpu/stat reading (atEnds() always returns true).
[CL] Store the data in maps by priority.
[CL] Added CpuLoadProxyObj.
[CL] Added BackendProxy.
[CL] Become a IQuarkComponentProvider.
[CL] Actually have the CpuLoadQuark.qml*
[CL] Fixed a typo.
[CL] Better aligned rectangles.
[CL] Linux backend now counts stuff properly at least.
[CL] Properly handle "sum" cpu.