Moved ShapefileLoader to core.

Moved the ShapefileLoader class to the ww-core project. The reason for
the move is that we will refactor it to be a generally useful class that
should be contained in core instead of being an example utility class.
Modified ShapefileLoader to be useful.

- Firstly, fixed the package declaration of ShapefileLoader.
- Then, to make ShapefileLoader useful, the RandomShapeAttributes
  variable called 'randomAttrs' was removed. The reason for this is that
  we do not want auto-generated attributes. Instead, we want to specify
  the attributes ourselves.
- To accomplish the abovementioned, a number of default attribute values
  was specified as static fields near the top of ShapefileLoader. These
  static values are used as defaults when constructing a
  ShapefileLoader. The actual attribute fields (such as pointColor,
  lineColor etc.) are now used in the createPointAttributes(),
  createPolylineAttributes() and createPolygonAttributes() methods
  instead of the random shape attributes that were generated before.
- Added getter / setter methods for the attribute values.
- Modified the createLayerFromShapefile() method by moving most of its
  logic to a new method, called populateLayerFromShapefile(). The
  populateLayerFromShapefile() is almost exactly the same as the old
  createLayerFromShapefile() exept that it isn't responsible for
  creating a layer (it receives a layer as parameter and populates it).
  Then, modified the createLayerfromShapefile() method to create a new
  layer and call the populateLayerFromShapefile() method. The reason for
  this refactor is that we want to populate existing layers from
  shapefiles instead of having to always get a new layer in return.
- Then added a new addRenderablesForPolygons() method that populates a
  layer instead of creating a layer for each group of
  'numPolygonsPerLayer' polygons.
Added ShapefileLayer.

Added a new class called ShapefileLayer. This class is responsible for
loading a shapefile by constructing URLs relative to a base filename.
The different files that are present during loading are .shp, .shx,
.dbf and a .prj file. The base filename serves as prefix for all of
these filenames. The shapefile gets constructed from these filenames and
the layer populated by making use of the ShapefileLoader class. The
default shapefile prefix points to "shapes/Empty". This represents a
default empty shapefile. Sub-classes can extend this layer and provide a
correct base filename.
Shapefile borders and coastlines layers.

Added two new classes called CoastlinesLayer and BordersLayer. These
classes extend from ShapefileLayer and loads their shapes from
Coastlines and Borders shapefiles respectively. The purpose of these two
layers is to provide an offline alternative to the
CountryBoundariesLayer. The only downside is that these layers might be
a bit more resource intensive to render and they are a bit lower
resolution when compared to the image-based CountryBoundariesLayer.
Also, it inflates the ww-core jar a bit.
Allow configurable WMS transparent texture request.

Fixed a bug in the WMSTiledImageLayer class where the 'transparent'
parameter of the constructed request URL had a fixed value of 'TRUE'.
This parameter is now set based on the <UseTransparentTextures> XML
clause in the worldwind.layers.xml configuration file.