Add a lint option to warn about while (true) { ... }

[catamorphism]

Now that we have loop{ ... }, maybe there should be a warning or lint flag to suggest changing while(true) {...} to loop{...}. (This will be helpful to the user as they may be able to remove spurious fails or unreachable calls.)

Since lint seems to just be concerned with ctypes right now, I'm not adding it yet since I'm not sure what the intent behind the current lint module is.

[graydon]

The intent of the module is to collect together every miscellaneous semantic check that there's any plausible disagreement over the warning-ness or error-ness of -- in terms of the severity a reasonable person might want -- such that users can control the warning-ness / error-ness themselves (using per-module attributes).

So this is an appropriate check. I expect lint will accumulate quite a lot of checks.