display added sub task
task updater removes deleted sub tasks
hide deleted sub task
new sub task button added
create new empty sub task in sub task list
create new empty sub task after clicking on new button
remove unnecessary bootstrap dependency
use text! instead of tpl! for require-text
use text! instead of tpl! for require-text fix
extract task and sub task styles from main.less
extract task and sub task styles from main.less
extract fading element from TaskView
remove unused variables in TaskView
delete button added to sub tasks
sub task destroys itself on delete
integrate sub task delete to its view
task triggers a change event on sub task destroy
make sub task draggable
introduce parent task id in data.json
allow sub task dropping onto other sub task in its own task