This commit also introduces a new CSSEvents object that is used to
abstract vendor specifics events related to CSS transitions and
animations.
Fixes#183.
Fixes#179.
The UI and the internal APIs are still rough around the edges but the
feature is basically working. You can now select multiple cards and
move them together or (un|)assign them a label.
The idea is that by displaying card details in a sidebar stuck on the
right of the screen, the mouse had to travel too much before
interacting with it. I also don’t want to use the Trello solution
(modal) on big screens, because I like the ability to interact with
the selected card and with the board at the same time (like in a
e-mail client).
The solution introduced in this commit consist of opening the card
detail in a column next to the minicard list.
This commit also fix right sidebar members and labels drag and drop.
