Page escape confirmation while editing added
Sample select values added

Base.py now handles sample select values for select inputs.
Select color's shade column added
Shade (select sample) element added
New element type - select - added

New element type select serves for select inputs.
It loads possible values list from server. List is the same
type as saved values list, you can edit it, add new values, remove
values and then use it as posible value in select input.
Select element added