layout fix: adapt column size dependent von number of columns configured

[cforce]

The columns get dsipayled vertical alligned in stead all in one row if i use more than 3 in my layout. The problem is that the .task_panel.width in css is alyways 31% but it shall be set dependn on number of columns configured. eg.

100% / (number of configured columns)= % for one columns size for css to set.