MainFrame: improve snapping behavior

Previously, we could mistakenly treat maximized state that was
entered with aero snap as our own snap. It produced problems when
the window was being dragged out of that maximized state.
This commit fixes that situation.
Don't exit "delay show not loaded" state on show
Don't paint logo in "delay show not loaded" state
Don't show toolbars in "delay show not loaded"

If exclusive seekbar was active when entering said state
Lower "delay show not loaded" duration