Enum not sorting alphabetically

[rbibby]

What is the issue?

ENUM values are sorted based on their index numbers, which 
depend on the order in which the enumeration members were listed in the 
column specification. For example, 'b' sorts before 'a' for ENUM('b', 'a').

Steps To Reproduce

1. Create an enum but don't have the options in alphabetical order in the database
2. Try and sort on the column and notice it is sorted by the enum index order rather than alphabetically

Expected behaviour

Sort alphabetically

Possible fixes

Needs some consideration on how to fix this, probably need to do some different sorting when the filter type is enum