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/closebutton.lua

@@ -57,7 +57,6 @@ function CloseButton:init()
             -- drawn. so use callback to get range at runtime.
             range = function() return self.dimen end,
         },
-        doc = "Tap on close button",
     }
 
     self.ges_events.HoldClose = {
@@ -65,7 +64,6 @@ function CloseButton:init()
             ges = "hold_release",
             range = function() return self.dimen end,
         },
-        doc = "Hold on close button",
     }
 end