This behavior allowed a command like this to run without error:
pgbackrest backup --stanza=db full
Even though it actually performed an incremental backup in most circumstances because the `full` parameter was ignored.
Instead, output an error and exit.
Suggested by Jason O'Donnell.
Now only two types of locks can be taken: archive and backup. Most commands use one or the other but the stanza-* commands acquire both locks. This provides better protection than the old command-based locking scheme.
Move command begin to C except when it must be called after another command in Perl (e.g. expire after backup). Command begin logs correctly for complex data types like hash and list. Specify which commands will log to file immediately and set the default log level for log messages that are common to all commands. File logging is initiated from C.
db-path was the only option with a hint so the feature seemed wasteful. All missing stanza options now output the same hint without needing configuration.
