fixes OpenTreeMap/otm2-addons#296

-Made the instance name column a fixed width with ellipses rather than
a horizontal scroll bar.

The primary goal of this screen is to edit the different instances.  Rather than having to scroll horizontally to click the edit button (requiring 2 clicks), I instead made the decision to limit the characters of column 1.  The instance name should be recognizable based on the number of characters shown and a user can click the edit button if they aren't completely sure.