Corpus, export, result selection

Add the possibility to choose which results are exported

show what will be exported and add options to select what is exported :

results (selected)
cqp indexes (selected)
[v] xml-txm pivot files (for annotation) (selected)
editions (selected)
temporary&extra files in a list (unselected)
- add a SELECT/UNSELECT ALL buttons

(from redmine: issue id 200, created on 2013/07/04 by Benedicte Pincemin)