Bare words now represent literal file names, and globs are a different
syntax shape called "Pattern". This allows commands like `cp` to ask for
a pattern as a source and a literal file as a target.
This also means that attempting to pass a glob to a command that expects
a literal path will produce an error.
with the `help` command to explore and list all commands available.
Enter will also try to see if the location to be entered is an existing
Nu command, if it is it will let you inspect the command under `help`.
This provides baseline needed so we can iterate on it.
Remove a number of unwraps. In some cases, a `?` just worked as is. I also made it possible to use `?` to go from Result<OutputStream, ShellError> to OutputStream. Finally, started updating PerItemCommand to be able to use the signature deserialization logic, which substantially reduces unwraps.
This is still in-progress work, but tests pass and it should be clear to merge and keep iterating on master.
