Filter out variables

[veimox]

In the same fashion as RosIntrospection::SubstitutionRule it would be nice to have a RosIntrospection::FilterRule to filter out unwanted variables.

Use case 1 I get a Twist Stamped but I am only interested on the twist, then I apply a filter to remove the header part. Once filtered, I can apply Substitution Rules to rename the vars if wanted.

Use case 1 I get a sensor_msgs/BatteryState but I am only interested in the percentage. I apply the filter and can use only the data I am interested in.

Ideal features

• We can define multiple filters per topic
• We can define rules with regex