Exclude original geometry from MVT

Currently, the original geometry is packaged into the vector tile, additionally to the MVT geometry. In order to make the size of tiles smaller, implement an option to exclude the original geometry from the MVT.

Example (tile index 13, 4457, 2833)

I took the query from Django and used it in pgadmin with pg_size_pretty(length(ST_ASMVT(...))). These are the sizes before and after I comment out the table."geometry"::bytea part:

with geometry: 360 kB
without geometry: 193 kB

Reduction of 46%

submarcos / django-vectortiles

Exclude original geometry from MVT #15

Example (tile index 13, 4457, 2833)