w2grid.js: Reset searchIds on clear()
w2grid.js: Reset searchIds on clear()

Otherwise the grid becomes messed up if searching was enabled.

ceedriic/w2ui,ceedriic/w2ui,ceedriic/w2ui,ceedriic/w2ui,ceedriic/w2ui,ceedriic/w2ui,ceedriic/w2ui