Merged move, tab move and resize states into new modifier state handling. Prevents multiple states being active at once.
Removed CToolboxWindow::AddButton (and m_buttons), drawing should be up to each window in the OnRender callback.
Wrapped WINAPI's window parent functionality to avoid the parent drawing over its children.
Removed custom window moving code, send move message to WinAPI instead.

This way we get default Windows effects "for free", like aero snap (including visual effects) and such.
Fix: Thick frame appearing while maximized.
Removed full path to startup splash.
Reworked docking system