Added WXView java class.

This class holds some of common parameters for each wxControl, and tells us if such control has been created yet.
Added WXNative java class.

This class is used to communicate from Java classes to wxWidgets, for now it contains only two methods wxStart() and wxEnd().
Added WXCalls java class.

This class contains static methods that wxWidgets should call. It communicatest together with WXApp to find correct views and frames, and manipulate them from wxWidgets.
Added WXApp java class.

WXApp is class that exists from creation of single application until very end. It is created before even first activity, and lasts until last activity is closed. It contains containers with all WXFrameActivity, WXView and some other static members that are fundamental for whole design.