review: add import comment

Change-Id: I1544e9fa57fa5f512b1b63f4aa3760dcb074b10c
review: add -n flag to show commands without running them

Change-Id: Id38ca5deeb72ee53f3a62c6a925e66f065686b83
review: push argument handling into subcommands

Will enable flags for subcommands.
Improves error checking already.

Change-Id: I19219fd4d05b605c89fe0d2b1241aafbb6f72dbe