Widgets sample: Button page

[kenz-gelsoft]

Implement the Button page's basic behaviors which is part of the wx's widgets sample.

Some TODO's will be resolved in another PR.

---

• Generate new wx Classes bindings
  • wxTextEntry
  • Mixed-in wxTextCtrl manually
  • wxItemContainerImmutable
  • Mixed-in wxRadioBox manually
  • wxIcon
  • wxBitmapButton
• Add and fixed some Builder pattern construtors
  • Add wx::BitmapButton builder
  • Fix constructor default styles for classes
• Add and expand wx generic wxList bindings
  • wxSizerItem
• Support following param types
  • wxDirection -> c_int
• Fix existing binding bugs
  • wx-returns non-ASCII string was cut off
• Support Additional Event types
  • (wx)EVT_CHECKBOX -> wx::RustEvent::CheckBox
  • (wx)EVT_RADIOBOX -> wx::RustEvent::RadioBox

[kenz-gelsoft]

TODO: fix windows build.

[kenz-gelsoft]

part of https://github.com/kenz-gelsoft/wxRust2/issues/61