Implement next and prev commands for GUI, timeline for GUI
Merge pull request #128 from liafailboy/working

animation for the category added
Merging step 1
Merge remote-tracking branch 'upstream/master'
Category SideBar slide back
Merge pull request #129 from mikelimantara/master

Working
editting
Merge branch 'master' into working
done for the animation og the cateory