sets the position and visibility of a sort arrow
| state | boolean | true/false to show/hide an image |
| ind | number | the index of a column |
| order | string | asc/desc - the type of an image (optional, "asc" by default) |
| row | number | one-based index of the header row (used in multirow headers, the top row by default) |
//minimal parameters set
mygrid.setSortImgState(true,1);
//maximal parameters set
mygrid.setSortImgState(true,1,"desc",2);
//hide the sorting image
mygrid.setSortImgState(false);