InputContainer: Fall cleanup ;).

Get rid of the doc & seqtext fields, as they are not actually used (nor
are they particularly useful, the event handler's name should be pretty
self-explanatory).

Also, tweak the key_events documentation to highlight the quirks of the
API, especially as far as array nesting is involved...

Random drive-by cleanup of the declarations of key_events & ges_events
to re-use the existing instance object (now that we know they're sane
;p) for tables with a single member (less GC pressure).

frontend/apps/reader/modules/readerpanning.lua

@@ -17,17 +17,25 @@ function ReaderPanning:init()
         self.key_events = {
             -- these will all generate the same event, just with different arguments
             MoveUp = {
-                { "Up" }, doc = "move visible area up",
-                event = "Panning", args = {0, -1} },
+                { "Up" },
+                event = "Panning",
+                args = {0, -1}
+            },
             MoveDown = {
-                { "Down" }, doc = "move visible area down",
-                event = "Panning", args = {0,  1} },
+                { "Down" },
+                event = "Panning",
+                args = {0,  1}
+            },
             MoveLeft = {
-                { "Left" }, doc = "move visible area left",
-                event = "Panning", args = {-1, 0} },
+                { "Left" },
+                event = "Panning",
+                args = {-1, 0}
+            },
             MoveRight = {
-                { "Right" }, doc = "move visible area right",
-                event = "Panning", args = {1,  0} },
+                { "Right" },
+                event = "Panning",
+                args = {1,  0}
+            },
         }
     end
 end