Add Custom Container (TODO: I cannot store more than one object in an array as an attribute...don't know why
A GlobalContainer is created in the global space for every Main Tag (TODO:  Fix the x,y coordinates at creation time )
Add placeholder-text for the global container
Make Global Containers droppable, now the main Tag is changed when drag and drop file representations between the containers
ExportObject.getSurroundingPapers
- add position awareness
- draw lines to aware-of papers
- create representation code cleanup
create and show export options
add some interaction functionality (demo)
small attribute adjustment
Merge branch 'develop' into exportObject