select target strategies

[maiermic]

At the moment, the first found candidate (of detected objects) is always selected as target, see: https://github.com/maiermic/robot-cameraman/blob/c1beeea87fe4f82e42eb5844df74782d92719b03/robot_cameraman/cameraman.py#L123)

Since this might not be the intended target, the user might want more control how the target is selected:

• The user should be able to select a target by clicking (in the bounding box of a candidate) on the live view
• A target should only be auto selected if a certain pose is detected (see pose estimation)
• A target should only be auto selected if it matches certain conditions (e.g. size, color, etc.)

[maiermic]

See --select-target-strategy. Certain conditions (e.g. size, color, etc.) are not supported yet, but might be added later.