* simplify GetItemByPath
* hub: sort version numbers by semver
* replace golang.org/x/mod/semver with github.com/Masterminds/semver/v3 (would not compare correctly)
* fix nil dereference with tainted items
* update tests for collections, postoverflows
* fix nil deref
* don't fallback to master if hub is not found, improve message
* explicit message for unknown version / tainted collections
* Fix suggest functional tests
* comments
* non-empty SubItems() implies collections type
* use "slices" from stdlib
* No need to repeat author field in the index -- take it from the item key
* Refactor hub URL/branch configuration
* docker: using --force to implement $DISABLE (required for items in collections)
* use pointer receiver for consistency
* csconfig: drop redundant hub information on *Cfg structs
* rename validItemFileName() -> item.validPath()
* Methods on hub object
* updated tests to reduce need of csconfig.Config or global state