Fix escaping from Textarea mode in input fields.

When escaping from Textarea mode in input fields, and also text areas if
'insertmode' is set, return to Insert mode.

vimperator/TODO

@@ -38,6 +38,7 @@ BUGS:
 - The MOW shouldn't close when executing hints and ;F isn't working.
 
 FEATURES:
+8 Document Textarea, Caret and Visual modes.
 8 Incremental searches should retreat to their starting position on <Backspace>
 8 Replace config.name tests in liberator with more specific feature
   tests or overridable APIs where at all feasible.

vimperator/locale/en-US/options.txt

@@ -494,10 +494,13 @@ ____
 |\'noim'| |\'noinsertmode'| |\'im'| |\'insertmode'| +
 ||'insertmode' 'im'|| boolean (default: on)
 ____
-Use Insert mode as the default for text areas.
-Makes Vimperator work in a way that Insert mode is the default mode for text areas.
-Useful if you want to use Vimperator as a modeless editor, keeping the known Firefox interface for editing text areas.
+Use Insert mode as the default for text areas. This is useful if you want to
+use the known Firefox interface for editing text areas. Input fields default to
+this behaviour irrespective of this option's setting.
+
+Textarea mode can be entered with *<C-t>* from Insert mode.
 ____
+// TODO: <C-t> is not hyperlinked as it's not documented yet.
 
 
 |\'ls'| |\'laststatus'| +