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/ui/widget/htmlboxwidget.lua

@@ -27,12 +27,10 @@ local HtmlBoxWidget = InputContainer:extend{
 
 function HtmlBoxWidget:init()
     if Device:isTouchDevice() then
-        self.ges_events = {
-            TapText = {
-                GestureRange:new{
-                    ges = "tap",
-                    range = function() return self.dimen end,
-                },
+        self.ges_events.TapText = {
+            GestureRange:new{
+                ges = "tap",
+                range = function() return self.dimen end,
             },
         }
     end