Properly transform a location into a coordinate when using a Proj4 projection

This is the start of a solution for [Issue #80](https://github.com/migurski/TileStache/issues/80). As `Goodies.Proj4Projection.Proj4Projection.project()` overloads `ModestMaps.Geo.LinearProjection.project()` and adds another argument to the function (`scale`), the original calls to `project()` do not work any longer, for example `ModestMaps.Geo.locationCoordinate()`, which is used in `tilestache-seed.py`.

I added an overload for `locationCoordinate()` to `Goodies.Proj4Projection.Proj4Projection`, which resolves the problem at least in my case. Apart from my EPSG:3035 use case, the patch is untested. Probably one should add a similar overload for `coordinateLocation()` so that the issue is resolved in the other direction as well.