cleanup in vector utils
start refactoring of the Processing mmqgis backend: Delete column and
Delete duplicate geometries
refactor Text to float alg
refactor Extract by attribute alg
refactor Select by attribute alg
refactor Grid algorithm
refactor Gridify alg. fix license headers
refactor Hub distance alg
refactor Hub lines alg
refactor Merge alg
refactor Geometry convert alg
remove old code
update Grid alg to avoid some coordinate precision issues