Option to ignore dev deps

[stevemessick]

Awesome tool, thanks!

I'd like to eliminate all dev dependencies in one swell foop. Rather than listing deps in --ignore-packages, how about an option to --ignore-dev-deps?

Update:
Here's the command to ignore all packages pulled in by a single dev dependency, package:test:
pubviz open --ignore-packages test,shelf_static,shelf_web_socket,http_multi_server,matcher,source_map_stack_trace,web_socket_channel,boolean_selector,pub_semver

It took several iterations to derive that. It is probably only valid for package:test version 0.12.6, and even for that version other packages could be eliminated (barback, glob, yaml are required by other packages as well as test). Letting the tool find all non-root packages with no incoming deps, eliminating them, and iterating would be faster. I dunno know how hard that is in practice for the general case with many dev deps. I only had one.