Changed keyboard to show on defined position.

* svghmi.js
added size paramter to edit_value
changed show_modal function to offset keyboard if paramter passed

*widget_input.ysl2
in on_edit_click:
function get position if key_pos element is defined in input widget

*widget_keypad.ysl2
Reworked keypad widget to extand class widget,
added support for changing keyboard position to user defined location

Reworked button widget so it uses classes.

SVGHMI: allow multiple variables and formatting in Display widget. Formatting is printf style and given as first argument. If no formating is given as widget argument, space separated.