Add blacklisted topics

[dimaxano]

Purpose

Sometimes we do not want to record some heavy topics like Image or Pointcloud.

Approach

Add ROS param blacklist_topics. If any of existing topics is in that list, do not subscribe to it.

Disclaimers

That implementation is not able to subscribe to the topics with non-default QoS policy, which makes it unable to subscribe to some sensor data (Imu, Images). So I add dirty fix for that here. Allow it to live here, please, until I return back with proper fix like described in this issue.

[dimaxano]

@guilyx @cmraaron

[cmraaron]

Its not a biggie, but it seems a bit fiddly with these repeated checks and temporary variables eg:

  if (topics.size() > 0 || blacklist_topics.size() > 0) {
    std::vector<std::string> topics_to_parse;
    if(topics.size() > 0){
      topics_to_parse = topics;
      options_.all_topics_ = false;
...

There are two ways to simplify this that immediately stand out to me.
One is to just use topics_, and treat it as either a whitelist if options_.all_topics_ == false, or a blacklist if options_.all_topics_ == true

Or if you prefer keeping separate topics_ and blacklist_topics_, then trust that the exception throwing will guarantee that we will never have both. Extract a function from the options_.[blacklist_]_topics_.insert( code, and call it twice. Once with (topics_, topics), the other with (blacklist_topics_, blacklist_topics)

[dimaxano]

@cmraaron I like the idea of having a single argument with topics names, so I added is_blacklist ROS parameter (all_topics you proposed, is an internal variable, not a ROS param, that is why I created new param)