Fix for Text Selection issues.

Fix for Text Selection issues.

  - Do not place the left and right selection handles
    in the same cursor position.
  - Do not recalculate the handles position when the
    text stops scrolling.
  - Stop the scroll timer when the text stops scrolling.
  - Remove the unimplemented methods SetScrollTickInterval()
    and GetScrollTickInterval() from the Text::Decorator.
  - Do not scroll to the beginning of the text if the
    'Select' button is pressed and the cursor is at the end.

Change-Id: I4db3cce902943fb1378f976ae622ad702a0a6790
Signed-off-by: Victor Cebollada <v.cebollada@samsung.com>