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* added AutoflushFile.seek()
* added AutoflushFile.truncate()
* added CPUTimeManager.set_refresh_each()
* added satella.instrumentation.cpu_time.get_own_cpu_time()

Build process
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* added pylint

Change-Id: I0d82869d91767b7aabbdfcad0148b076799fa3e9

* exposed `dump_frames_on`

added `CancellableCallback`
`CallbackGroup` will now support `CancellableCallback`s as well
`MemoryPressureManager` will now use `CancellableCallbacks`

* added __eq__ methods to Traceback classes
* extended Traceback to fetch current stack frame if no exception is in progress and no stack frame is given
* added a feature to load a Traceback from a stream

extended Traceback to fetch current stack frame if no exception is in progress and no stack frame is given