add option to turn off e-ink optimization

which currently just sets free the limitation of panning gestures
emitting rate. This should fix #1039 when unchecking the
"E-ink optimization" in the "Screen settings".

frontend/apps/reader/modules/readerrotation.lua

@@ -35,7 +35,7 @@ function ReaderRotation:init()
                         w = Screen:getWidth(),
                         h = Screen:getHeight(),
                     },
-                    rate = 0.3
+                    rate = 0.3,
                 }
             },
         }