Assume desk name from current directory

It would be nice if desk would assume the name of the desk to load from the cwd if no desk name was given, e.g:

```
$ cd ~/myproject
$ desk .
$ desk

myproject
desk of my project
...
```

Start at the CLI entry point for desk and trace how an omitted desk name is handled, then inspect the existing path-based loading behavior. Done means `desk .` loads the desk named from the current directory and a subsequent `desk` command loads that same desk without an explicit name.

Written by the indexing model from the issue text.