Debug statements etc

[willtebbutt]

We have quite a lot of @debug statements floating around the code base, and I wonder how much additional value a lot of them provide. Debug messages like @debug "run model..." in a function called runmodel really don't provide any additional information over and above what a stack trace already provides, while cluttering the code.

I would be keen to understand whether

1. anyone feels that these debug messages provide value over and above what we get for free from stack traces and
2. there would be any objections to removing a lot of the debug messages.

[yebai]

@willtebbutt That's a good point - many of these codes are written when Julia's debugging environment is less mature. Indeed, some @debug messages are a bit redundant and can be safely removed.

[willtebbutt]

Great. I'll do this once #513 is merged.