Command to iterate over robots with a certain name

[kostmo]

Multiple copies of a robot with a given name can be placed on the map via palette entries (see also #1396). In goal checking logic, we may want to iterate over all robots of a given template.

The robotnumbered command was used in the gated_paddock scenario (#835) to iterate over sheep robots, since at that stage within the scenario, sheep were the only robots.

However, in a scenario with lots of growing plants, it is inefficient to use robotnumbered to find the desired named robots.

robotnamed will simply return the first instance of a robot with a given name, which does not facilitate iteration. I tried using selfdestruct within a loop inside the goal logic, but this does not remove the robot from the robotnamed lookup table soon enough to facilitate selection of the next robot; the attempt to iterate through all robots of a given name by selfdestructing them resulted in an infinite loop.

There should exist a command that returns a list of all robots with a given name. Perhaps a more general command could list of all robots that satisfy a certain predicate, but note that currently a given robot's name is not queryable.

[byorgey]

Related: #506