added, global user data for grid

[matak]

this commit add possibility to set user data for grid not only for row

http://docs.dhtmlx.com/api__dhtmlxgrid_getuserdata.html

gets user data mixed getUserData(mixed row_id,mixed name);

Parameters row_id mixed row id, if empty, user data of the grid (not of a row) name mixed name of the user data

//get global user data var userdata = myGrid.getUserData("","someName1");

[matak]

is there any problem with this request? dont you like it?

[Stanislav-Wolski]

Sorry for delay. Merged in the main codebase