Added info overlay part

[JoeSiu]

a simple Info overlay that adds texts overlay to the camera images, might be useful for debugging. It can show the current fps if enabled (#897) as well as the current throttle and angle, or any other info by adding the inputs or by calling the 'add' function in InfoOverlayLogger.

[DocGarbanzo]

@JoeSiu - thanks for your PR. Why would you want to put this data into the images, as they are used for training. This would distort the ability to learn. You have another PR where the car frequency data gets logged. This is more useful I think.

[JoeSiu]

@DocGarbanzo This part is mainly used for easier debugging. For example, when testing the stop sign detection, It's easier to see the current pilot's throttle as well as the bounding box for the stop sign directly on the camera image while using the mobile app or web controller, instead of checking the output from the shell in a separate window which I think is less convenient. It will indeed affect the training through which I didn't consider at first, sorry about that!

[DocGarbanzo]

We can do this, pls have a look at the comments.

[DocGarbanzo]

@JoeSiu - thanks for addressing / solving all change requests. This looks very good to me now. Can you please do one last step and that is rebasing your branch on dev (this will require resolving some conflicts as complete.py got updated in the meantime), squashing your 3 commits into 1 and then force pushing your branch? This will create a single commit into the repo that keeps the history linear & I can merge this.

[JoeSiu]

@DocGarbanzo I have rebased the branch, thank you!

[DocGarbanzo]

Sorry, I have a couple of only minor comments, can you have a look at them?

[DocGarbanzo]

What is the reason for this member to be a class member and not an instance member?

[JoeSiu]

@DocGarbanzo It is used so that info can be written directly from other parts like this and have a shared info_list

from donkeycar.parts.info_overlay import InfoOverlayer
InfoOverlayer().add("hello")

"hello" can then be written onto the image along with other info like throttle or angle. However, it is supposed to be used as a temporary method in this case for easier debugging.