Summary:
Issue 1: If you drop text to elm_entry, text is inserted twice.
Reason: Drop callbacks are registered multiple times in elm_entry.
Resolve: Register only one drop callback at entry side.
Issue 2: Even thought entry is disabled, non-editable, you still can drop text, image file. (Example, run Entry Scrolled and drop text, image file to disabled or non-editable entries).
Reason: Drop callback are registered but not remove when entry is set to disabled, non-editable mode.
Resolve: Correct registering and removing drop callbacks in entry.
Reviewers: JackDanielZ, raster
Reviewed By: raster
CC: woohyun
Differential Revision: https://phab.enlightenment.org/D565