Add RateLimitedRepeater to basic_apps

[wingo]

This app is useful for generating different load levels. No documentation because the documentation files changed name in next and this is based on master, and the basic_apps documentation doesn't currently specify anything about the API of those applications, so documentation seems to be a moot point currently.

[eugeneia]

I think this is too fancy for apps.basic_apps and belongs under apps.test.*. What do you think @lukego?

[wingo]

Sure, or apps.rate_limiter; dunno. Or, perhaps we could add a mode to the RateLimiter that doesn't discard packets.

[wingo]

Somewhat related to the #656.

[eugeneia]

@wingo I like the idea of extending RateLimiter and combining it with Repeater. It seems like a nice composing solution, but the choice is yours.

[mwiget]

@wingo I like the idea as well. While one could chain a RateLimiter after the Repeater app, it burns avoidable CPU cycles by first creating the packets, then dropping them mid flight. Had to combine RateLimiter also in my crude snabb based lwaftr flow generator in order to have enough CPU cycles to count incoming traffic.

[wingo]

Closing this one; #793 is the successor.