Minimize the use of explicit `try`/`catch`

Reason

try/catch is verbose and non-trivial uses are error-prone. try/catch can be a sign of unsystematic and/or low-level resource management or error handling.

Example, Bad

void f(zstring s)
{
    Gadget* p;
    try {
        p = new Gadget(s);
        // ...
        delete p;
    }
    catch (Gadget_construction_failure) {
        delete p;
        throw;
    }
}

This code is messy. There could be a leak from the naked pointer in the try block. Not all exceptions are handled. deleting an object that failed to construct is almost certainly a mistake. Better:

void f2(zstring s)
{
    Gadget g {s};
}

Alternatives

• proper resource handles and RAII
• finally

Enforcement

??? hard, needs a heuristic