Support tile mode

[ivorbosloper]

When trying to access a published layer with tile-mode it results in an error msTileSetup(): CGI error. Tile API is not available. If this is the expected behaviour of this docker image, please close this issue.

Example url: http://mapserver:8080/?layer=polygons&mode=tile&tilemode=gmap&tile=0+0+0 .

I traced it down to a missing cmake -DUSE_PROJ=1 option in the Dockerfile builder target. Without this option, after running cmake the mapserver-config.h contains an out-commented /* #undef USE_PROJ */ and the tile-mode feature is not compiled.