Create a UI debug control

[lucaswoj]

We should consider adding a mapboxgl.DebugControl class which adds UI controls for toggling "tile debug" and "collision debug" modes (and future debug capabilities).

ref #2281 (comment)
ref #2284 (comment)

cc @bhousel @mourner @jfirebaugh @ansis

[lucaswoj]

I feel mildly 👎 towards this proposal on the grounds that

• we should add as little debugging code to the distributed mapbox-gl.js as possible
• toggling tileDebug and collisionDebug is easy from the console
• users who are likely to find tileDebug and collisionDebug useful are likely to be designers within the Studio interface or developers comfortable using the console

[mourner]

I don't see the need for a dedicated control — a debug page and ability to use console are enough.

[bhousel]

Then why open an issue for it?? Just to tell me my idea sucks?

In the amount of time we have discussed it, I probably could have built the damn thing. I did most of a geolocation control yesterday in like 2 hours.

This is nuts.

[mourner]

Then why open an issue for it?? Just to tell me my idea sucks?

Not at all! I'm sorry it looked that way. 🐼 We open an issue for any improvement idea to have our decisions documented and easily searchable. Sometimes this can be an overkill, but we all make mistakes sometimes. ❤️