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/readertoc.lua

@@ -36,11 +36,7 @@ local ReaderToc = InputContainer:extend{
 
 function ReaderToc:init()
     if Device:hasKeyboard() then
-        self.key_events = {
-            ShowToc = {
-                { "T" },
-                doc = "show Table of Content menu" },
-        }
+        self.key_events.ShowToc = { { "T" } }
     end
 
     if G_reader_settings:hasNot("toc_items_per_page") then