Create new ui package
Create new components package
Add proportional spinners

Fixes #503. See also #443.
Oops, I wasn't setting UOMs correctly

Note: This doesn't work with localized strings for now
Make sure max is always >= min.
Remove unused class
Fix a localization problem for WKN
Improve the Util class
Updata javadoc for components package

Left to do:

    * Update javadoc for panels package
    * Fix UniqueSymbolPanel constructor / inheritance
    * Reorganize inheritance in the ui package
    * Make a Preview panel

Later:

    * Extract classification panel elements
    * Extract classification computation methods into a computation
      package
    * Add a lock for symbol width / symbol height and maintain the
      aspect ratio
    * Add a preview for the minimum size in proportional legends
Clean up unique symbol/proportional panels
Add missing methods to IInterpolationLegend
Make IInterpolationLegend extend LookupFieldName
Fix field combo boxes (esp. prop point/line)

Remove the vestigial field combo boxes that were previously causing init
problems.
Move components to the components package
Simplify constructors
Push setGeometryType down (it was empty elsewhere)
Introduce PreviewPanel
initPreview should have been abstract up top
Prefer "OK" over "Ok".
Clean up UIPanel methods