Added support for TMT10-plex isobaric tags.
Merged with the Florian Breitwieser's latest master version
Code FIX in order to make isobar compatible with R version 2.10.
Otherwise it would only run with R 2.14. This is all because the system.file
function has a new argument that is not compatible with older R versions
(one of these lovely R catches)
Merge pull request #2 from florentgluck/master

Merge Florent Gluck's changes back to upstream