Before this commit, the threshold was the amount of "fuel".
Now, it is the maximum number of instances used to solve a TC problem.
We have two thresholds
- `maxInstSize`: default 128
- `maxCoeSize`: default 16. It is similar to `maxInstSize`, but used for automatic coercions.
cc @Kha
@Kha Not sure whether we should have an option for supressing this
information or not.
We need this information for diagnosing problems. For example, I was trying to
understand why the elaborator was looping. I suspected it was the
TC module, but I was not getting any trace messages since the symbol
was overloaded, and the case that did not work was the expensive one :(
