added device visible constants in Kwf_Component_Data

can be used everywhere where one of these three is needed
added new column device_visible for Kwc/Root/Category

now its possible to specify every page mobile visibility
added function getDeviceVisible for Kwf/Component/Generator/Abstract, Kwc/Root/Category/Generator and Kwf/Component/Data

this will return the correct used device visible
-> Kwf/Component/Generator/Abstract getDeviceVisible returns all because this is the default value, can be overriten for every generator if you want a specific device visibility
-> Kwc/Root/Category/Generator returns if mobileBreakpoints are set the correct device visible
-> Kwf/Component/Data it will look in his generator for the getDeviceVisible function
added the correct cssClass and style for the device visible in Kwc/Menu/Abstract/Component

now its possible to hide menu entries on mobile or show only on mobile
added some tests for the device visible functionality in Menu
param _useMobileBreakpoints is now optional for Kwc/Root/Category/Generator.php

if it is not set it will get his value from config
bugfix for Kwc/Root/Category/Generator getDeviceVisible function

returns now correctly parent function
optimized comment for Kwf/Component/Data function getDeviceVisible
extended menuDeviceVisible tests
Merge pull request #46 from kaufmo/3.3_pages_device_visible

pages device visible