Surveyor: refactor buffering code

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
Surveyor: flush buffers and reset them

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
Surveyor: new actor type -> MatrixOwner

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>