Defer and avoid loading some dependencies.

Every command is loaded before any command executes, so avoiding
unnecessary dependencies impacts all dzil commands.

Differences:
```
  cd /var/empty;
  dzil nop
```
  Savings:
   -  17 dependencies
   -  0.05 wallclock seconds
   -  13 Megabytes of memory
   -  5 involuntary context switches