Additional kp functionality and flags

[busstoptaktik]

With the reincarnation of the Plain context provider and its support for handling ancillary data, kp has become rather capable recently, but there are still some obvious holes in the functionality.

Obvious because in an abstract geodetic tool landscape, we may consider kp to sit as the third vertex in a triangle, where the two other vertices comprise the PROJ command line tools proj and cct. Or perhaps even the third vertex in a tetrahedron, with the PROJ geod program sitting in the fourth out-of-plane vertex. So we should expect kp to cover more or less everything these two (three) do. And more or less none of what their cousin cs2cs does, since that is entirely out of scope for Rust Geodesy.

Hence kp should gain at least some of these items:

• Handle binary input and output: Conversion from text to floating-point binary is a very slow proces, and as kp is intended a.o. as a filter in a data processing pipeline, feeding binary stuff from and to neighbours in the pipeline should speed things somewhat up
• Have better facilities for selecting 2D and 3D input and output
• Provision for including the input record (either in its entirety or through a tag column) into the output record for information and/or for synchronisation
• Prolong the road already taken with the implementation of the geodesic and the curvature operators: More access to the ellipsoidal primitives!
• Show scale factors (i.e. the proj's -S option, and the proj_factors entry of the PROJ 4D-API.
• ...and probably a bunch more