[Lazarus] LCL Grids: AscImageIndex/DescImageIndex

[Alexey]

I like when props almost sorted by name. AscII / DescII will be not 
sorted, other props will mess it.

So suggestion: names

- SortAscImageIndex, SortDescImageIndex

or

- ImageIndexSortAsc, ImageIndexSortDesc

-- 
Regards,
Alexey