SequencesLoader : add new extensions support

Signed-off-by: Jean-François Erdelyi <jean-francois.erdelyi.1@ulaval.ca>
remove debug statements and update the manual

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
Resolves-bug: https://github.com/sebhtml/ray/issues/176