simple hook for shelves and planks

Simple hooks for mounting to shelf planks. Easy print, no STL because customizer. and customization needed anyway.
Preset of top guide is rather thin because set for under-drawer hooks and below doors of wall boxes, while drawers and doors still need to be able to close. As the hooks are fixed with a screw which carries good part of the load, lack of top guide strength isn't much of an issue. These hooks aren't meant for heavy loads anyway.

// v0.4 20241013 option to remove any or all guides, fastening bores configurable
// v0.3 20240904 minor arc and blob optimizing
// v0.2 20240903 comments, cosmetical
// v0.1 20240901 initial version