Allow more supported input formats

[frankbroniewski]

It would be nice to have more than just shapefiles available as an additional input source. Since the Shapefile itself is quite limited when it comes to column name length it would be nice to have another alternative available, especially for using the column name matching algorithm.

In import_shp_dialog.py, line 83 self.shplayer = QgsVectorLayer(filename, filename, "ogr") is used so it would be quite simple to add more file types as input. Probably the existing shapefile importer and column matching algorithms could be more or less reused.

I am exporting our data from our GDI into a SpatiaLite database which holds only the optional and of course the required columns for each item. So at least for us it would be nice to have the option to load data from SpatiaLite databases as well.

[jaykayone]

Thanks, we will integrate this at the next revision