I'd like to make a world map using the Kravayskiy7, however QGIS seems to be unable to handle the projection, even though it is supported by proj4. 704900 (as is the EPSG for kav7) is not listed in the CRS and strangely when I try to define it manually using
+proj=kav7 +lat_0=0 +lon_0=0 +x_0=0 +y_0=0 +a=6371000 +b=6371000 +units=m
QGIS tells me that it's invalid (site for definition source). I always assumed that QGIS supported all projections that are featured by proj4. So why is QGIS behaving this way and how could I work around this?