add picking in qtQGLV
replace libXml2 by tinyxml2
resolve bug of leaving markers after removing darts
resolve bug of deleted marked darts
cmake find module for tinyXml2
Merge branch 'develop' into 'develop'

Christmas merge

See merge request !24
Merge branch 'develop' into 'master'

Christmas merge ..

See merge request !25
Merge icube-forge.unistra.fr:cgogn/cgogn