CheckBox related issues

[generalloki]

Here we collect CheckBox related issues and problems.

We need to implement more features from wxCheckBox: https://docs.wxwidgets.org/3.0/classwx_check_box.html

Add styles:

• wxCHK_3STATE: Create a 3-state checkbox. Not implemented in wxOS2 and wxGTK built against GTK+ 1.2.
• wxCHK_ALLOW_3RD_STATE_FOR_USER: By default a user can't set a 3-state checkbox to the third state. It can only be done from code. Using this flags allows the user to set the checkbox to the third state by clicking.
• wxALIGN_RIGHT: Makes the text appear on the left of the checkbox.

[generalloki]

We have implemented al features of wxCheckBox, so for now I am closing this issue.