Fixed crucial error when creating shapefile

I realize you probably don't update this anymore, and that there are many other alternative readers, but since you had improved on people's works before you I thought I would just clean up those errors so it's at least usable. It works :) Though the fact that it loads all records/shapes at once makes it a bit limited. 

Anyway, I think the errors were a result of changes in some methodnames to have
a leading underscore in the Shp module but forgetting to update those
names in the ShpFeature module. Also some syntax errors that had crept in there. Btw, I think the diff file is a bit off, I didn't change all the things it said I did.