Strip coordinates before splitting

This is for when the coordinates are read in from an external source and
contain leading or trailing space, which would otherwise result in an
empty coordinate.
Exclude .DS_Store file and include test kmls

- we need the test kmls in the repository to run tests
Add the test kmls so we can run tests
Test the stripping of the coordinates field
Polygons can have multiple inner boundaries

This update still allows the old way of setting a single inner bounday
via equals:

polygon.inner_boundary_is = LinearRing.new(...)

Is adds support to assign as array:

polygon.inner_boundary_is = [
  LinearRing.new(...),
  LinearRing.new(...)
]

Or add to the existing array:

polygon.inner_boundary_is << LinearRing.new(...)
polygon.inner_boundary_is << LinearRing.new(...)

I have added a test for this
Alias objects as features

This allows you to loop over the features in the KMLFile in the same way
you loop over features in containers
Specify the dependency on builder
updates