Eliminated tracking; use match instead

No need to keep match and track separately. They are essentially the
same thing.

As implemented now, when sourceLoc is specified, we do a comparison at
the same location. When it's not specified, we do a full screen search,
i.e., track.

Added/expanded support for relativeAOI. Now matched sig will generate a
special AOI with id="__MATCH__". When you specify a "relativeAOI", the
xywh are relative to the top-left corner of the matched sig, instead of
a regular AOI that uses absolute coordinates.

The track code is still kept in the source; will remote later.

To-do: the logic should be:
Match: source.png
sourceLoc: xyhw
destRange: xyhw, which can be identical to above or a different range.
We then search in that range. If missing, the default is ... either
sourceLoc or full screen.
adding destRange in the code

not yet supported by video2aoi.py
converting 1920 to 1680 screen size

using excel; also fixed startFrame