Fixes erronous grid shift ordering: use [dy,dx] for cp.roll axes

[Fredrikhb]

This is a fix specifically for how cp.roll is being used. (This intentionally excludes my other orientation fix (transpose on publish, polygon x/y., which fixes the rotation of the whole elevation grid.)

Problem: As the robot moves, the entire elevation layer creeps diagonally and stretches features.

Cause: cp.roll(..., axis=(1,2)) expects shifts as [rows(y), cols(x)]. Code used [dx, dy] inside the methods "move" and "move_to".

Fix: Pass [dy, dx] as argument to shift_map_xy instead of [dx, dy].

Evidence: before fix, map shifts diagonally on each update call. Origin of the whole elevation_map_raw becomes gradually shifted and features gets stretched into ridges as a result. After fix, map remains anchored to map frame and features are accurately captured where they are. Origin of elevation_map_raw remains consistent with base_link.

Both pictures are taken at exactly 10.0 seconds of simulation time, without and with fix respectively.

Before:

After: