tmf: CtfTmfContext rename

tmf: CtfTmfContext rename

Renamed from CtfTmfLightweighContext (there are no heavyweight
contexts anymore) + fixed the clone() method.

After much experimentation, I gave up trying to not make those
extend TmfContext (sorry bug 387929). It seems the iterator
manager depends on CtfTmfContext.equals() to not be overriden.

Fixing this behavior (by making the manager track the locations
instead of the contexts, for example) works, but then reading
events becomes unbearably slow.

I think it's better to not touch this until a proper iterator
API comes to TMF, at which point we can use that directly.

Change-Id: I57cedac2702d0b70950687bdfa7a681ac7582be8
Signed-off-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Reviewed-on: https://git.eclipse.org/r/10194
Tested-by: Hudson CI
Reviewed-by: Patrick Tasse <patrick.tasse@gmail.com>
IP-Clean: Patrick Tasse <patrick.tasse@gmail.com>