MTSTat: Refactored to support searching for changes

The new -c or --changes parameter allows to search for gesture changes
introduced by code changes, which is very useful for testing and
validating code changes or for searching for real-world log files for
regresion tests.

BUG=chromium:259532
TEST=run mtstat -c

Change-Id: I5b5d778144085426abb66408bc3e331d6ff450e7
Reviewed-on: https://gerrit.chromium.org/gerrit/62392
Reviewed-by: Dennis Kempin <denniskempin@chromium.org>
Commit-Queue: Dennis Kempin <denniskempin@chromium.org>
Tested-by: Dennis Kempin <denniskempin@chromium.org>
3 files changed