Add query option `--geometry` (`-g`)

[clarisma]

Applies geometric transformations to geometries retrieved by a query.

Proposed format: -g=<command>+

Where command can be one or more of the following:

• buffer(m): Buffers each geometry by a given distance (in meters)

• simplify(m): Generalizes each geometry with a given tolerance

• densify(m): Adds points to each geometry to ensure points are no more than m meters apart

• rotate(deg): Rotates each geometry

• scale(factor): Scales each geometry

• translate(xd,yd): Moves each geometry by the given distance in meters.

• project(srid): Projects each geometry

• validate: Checks geometries for validity, turns them into empty geometries if invalid.

• fix: Checks geometries for validity and attempts to fix invalid ones (e.g. node self-intersecting polygons)

• flip / mirror ?

• command to set winding order

Open issues

• Should this be called --transform (-t) instead to apply non-geometric transformations (e.g. change tags?)
  • if so, would need to change current use if -t to -k as proposed by #73.
• Does it make sense to offer union, intersection, difference?
  • If so, what are the features? What happens to the tags?