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

# pylint: disable=undefined-variable

from __future__ import absolute_import
from svgui.pyjs.jsonrpc.jsonrpc import JSONRPCServiceBase


class JSONRPCService(JSONRPCServiceBase):

    def serve(self):
        return self.process(request.body.read())

    def __call__(self, func):
        self.methods[func.__name__] = func
        return func