Remove old manipulation string classes and tests.

Signed-off-by: Hugues Peccatte <hugues.peccatte@gmail.com>
Remove old manipulation string classes and tests.

Signed-off-by: Hugues Peccatte <hugues.peccatte@gmail.com>
Add multibytes constants.
Update string tests.

Signed-off-by: Hugues Peccatte <hugues.peccatte@gmail.com>
Merge branch 'master' of https://github.com/phpmyadmin/phpmyadmin