adds new controller preparing to add end session on deadline functionality
Removes export panel in favor of directly exporting from the overview.
Fixes logger title.
Removes unneccessary import.
adding validation to add reqs panel
adds cancel buttons to the session
Merge branch 'dev' into dev-endSessionAfterDeadline
Implement error checking for non-deck voting
fixes bug that cancelled session is listed as open session
adds cancelled session branch to overview tree
Add comment
Rearrange code
Add comment
adds number of sessions for each branch in the overview tree
Store a card's value in its GUI text field
Add comment
Reimplement the method getting values from a deck
Refactor the code
Modify the method getting card's value

Change check null string to check empty string
adds table model in support for refreshing the tree