continued work on BTextView:

* reverted my recent change that caused Mail to always show the end
  of mails 8-) and now invoke ScrollToOffset() wherever it was missing
  (mostly in keyboard-related methods)
* _DoInsertText() only moves the caret if the text has been inserted
  in front of the caret, not after it
* overhauled selection by char/word/line and their extension mechanism
  (which now behaves as the haiku shell)
* use strnlen() instead of strlen() in those versions of Insert() which
  accept a length parameter, as strlen can potentially waste a lot of
  cycles skipping the whole string, when all we want is to clamp the length.
* cleanup (some of it automatic removal of trailing whitespace)

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@29995 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/os/interface/TextView.h

@@ -303,6 +303,9 @@ private:
 									float* outAscent, float* outDescent,
 									float* ioWidth);
 
+			int32				_FindLeftWordBoundary(int32 offset);
+			int32				_FindRightWordBoundary(int32 offset);
+
 			float				_StyledWidth(int32 fromOffset, int32 length,
 									float* outAscent = NULL,
 									float* outDescent = NULL) const;