My spell checker says "receival" should be "reception". Also, the
terms allow list and deny list are preferred over whitelist and
blacklist. But since scripts may depend on the shell command name,
only the help description is changed, not the cmd names.
Previously `shell_commands` was a "catch-all" module that included
shell commands for each and every used module that has a shell
companion. Instead, the new `shell_cmds` module is now used to provide
shell commands as individually selectable submodules, e.g.
`cmd_gnrc_icmpv6_echo` now provides the ICMPv6 echo command (a.k.a.
ping).
To still have a "catch all" module to pull in shell commands of modules
already used, `shell_cmds_default` was introduced. `shell_commands`
depends now on `shell_cmds_default` for backward compatibility, but
has been deprecated. New apps should use `shell_cmds_default`
instead.
For a handful of shell commands individual selection was already
possible. Those modules now depend on the corresponding `cmd_%` module
and they have been deprecated.
