The user can now query for all location information with
`mm_modem_location_get_full()', or just for specific location sources with
`mm_modem_location_get_3gpp()', `mm_modem_location_get_gps_nmea()' or
`mm_modem_location_get_gps_raw()'.
Renamed `MMCommonLocation3gpp' to `MMLocation3gpp', and removed the
`MMModemLocation3gpp' provided in libmm-glib. We'll just use the original one
from libmm-common always.
