RFE#908: Improvements for the table editor (index creation).

RFE#908: Improvements for the table editor (index creation).
https://sourceforge.net/p/phpmyadmin/feature-requests/908/

![rfe_908](https://cloud.githubusercontent.com/assets/6863616/3634119/1ca53098-0f17-11e4-8303-84c12b433655.png)


Signed-off-by: Ashutosh Dhundhara <ashutoshdhundhara@yahoo.com>