Windows & X11: Window::set_resizable (#558)

* Windows: Window::set_resizable

* X11: Window::set_resizable

* Code style regarding resizable

* X11: set_resizable remember max/min window size

* Stub out set_resizable on Android, iOS, and emscripten

* remove comment block from docs

* Windows: set_resizable in fullscreen

* Special case Xfwm

* Added fun provisos to docs

src/platform/emscripten/mod.rs

@@ -462,6 +462,11 @@ impl Window {
 
     #[inline]
     pub fn set_max_dimensions(&self, _dimensions: Option<(u32, u32)>) { }
+    
+    #[inline]
+    pub fn set_resizable(&self, _resizable: bool) {
+        // N/A
+    }
 
     #[inline]
     pub fn show(&self) {}