- added new module 'convenience'

convenience:
- added new submodule 'object_oriented': added function alias_property from GeoArray

geo.projection:
- EPSG2Proj4(): catched case EPSG_code=None
- EPSG2WKT(): catched case EPSG_code=None
- WKT2EPSG(): catched case wkt=''

io.raster.GeoArray:
- moved GeoArray, NoDataMask, CloudMask, BadDataMask, MultiGeoArray to a new separate library called 'geoarray' and added DeprecationWarnings instead

- updated some import statements

- updated __version__