Remove unused PointHandle class
FileFunctions: use varargs run method syntax
SwingDimSelectionWidget: add FIXME reminder

The DimSelectionWidget interface now exists on imagej-common's master
branch, but we cannot switch to it until a new imagej-common is released
and this imagej-ui-swing component is updated to depend on it.
SwingDimSelectionWidget: simplify min/max dim code

There is now an API in ModuleItem that allows for accessing extra
key/value pairs, so let's use it.