This fixes an issue where, upon the first call into weston_wm_window_read_properties after the hints->decorations property had changed, the old value for this property was read in weston_wm_window_read_properties
XWayland: When maximized, don't draw window decorations for windows that draw their own

This patch fixes an issue where window decorations were drawn for
fullscreen XWayland applications that draw their own window decorations
(eg. Google Chrome/Chromium)
XWayland: max/unmax: never overwrite saved window size with a maximized or full screen size

In order to handle going to a mazimized state from an already maximized
state, we need to make sure the saved size from when the window was
unmaximized is not overwritten with the size of the window in the
maximized state.
XWayland: Don't allow a maximized window to be moved via a self-drawn titlebar

When we have a window that draws its own decorations, including a
titlebar that can be used to move the window around, make sure that
this doesn't work when the window is maximized.