Dev#12997 training list

See merge request !513

year is kept while editing sessions & trainings

sort by date implementation

better layout

* replace ul / li by table
* add select to choose the year to display
* sortable table

Master

See merge request !511

Hotline 6.55

See merge request !510

Hotline #17249 auto open vertical menu

See merge request !501

Hotline #17335 fix removing widget in banner

See merge request !499

Dev#16866 cacher formation

See merge request !508

Hotline#17512 cannot validate menus modifications

See merge request !509

add hint in show / hide button

visibility implemented in training widget

visibility status implemented in /formations url

backoffice: add action show/hide

Dev#16803 display sessions for all users

See merge request !504

Dev#16126 custum link fields

See merge request !503

Sandbox#16325 unimarc view and download in inspector gadget

See merge request !506

refactoring for better understanding

hotline_#17335_fix_removing_widget_in_banner split class test to dispatch and post dispatch test case