load and rm are not intuitive

[harleypig]

pdx load for adding files and urls and pdx rm for removing them is not intuitive.

Either load/unload or add/rm (or both, i.e., load with an alias of add) would be more clear and intuitive.

Also, a mv option would be nice. A use case would be I realized I'd accidentally created a tests directory under my tests directory and put a bunch of files there, then loaded them. I know I can do pdx rm tests/tests/* then pdx add tests/*.