tasks #6738 - Draw bar chart with d3

Change-Id: Iacb874a490339f3d59fb418f556fb754547e4d93
tasks #6747 Draw grouped charts

Change-Id: Ia642eb2811e238f6fad97b8fd849d06f042aaffc
Explode graph.js in multiple scripts

Change-Id: I3e0a7faf92e0ebfb716bd41be6d1a63bf8837a68
Bars should be rounded only on top + animation

Change-Id: Ie751eb25828e120462da7b8d7bbab875badd4503
Gradient on bar and grouped bar charts

Change-Id: I04a87bafe8787d81066e6ef966d73ed6c46eb1ca
Add legend box

Change-Id: I37c1f0a2af023cefdf93204e0549f929ab371d45
Display description as title attr

Change-Id: Id8fc5cedd3979a02a6955eed4839bb4b315725ab
Refactoring: extract common methods

- gradients definitions
- build of legend box

Change-Id: If697d341a280f0fa0ba467f6e80fb7b0d375bb02
Merge remote-tracking branch 'gerrit/6669_draw_pie_with_d3' into tuleap-stable-master

* gerrit/6669_draw_pie_with_d3:
  Refactoring: extract common methods
  Display description as title attr
  Add legend box
  Gradient on bar and grouped bar charts
  Bars should be rounded only on top + animation
  Explode graph.js in multiple scripts
  tasks #6747 Draw grouped charts
  tasks #6738 - Draw bar chart with d3

Change-Id: I14ae47868c1db3f9775428b28138968354964ade
Tuleap 6.12.99.85

Change-Id: I2408376f7adfeea2796db06c62e26431f74b6ef9