scripts: Adopted dat tweak in other scripts

This just makes dat behave similarly to Python's getattr, etc:

- dat("bogus")       -> raises ValueError
- dat("bogus", 1234) -> returns 1234

This replaces try_dat, which is easy to forget about when copy-pasting
between scripts.

Though all of this wouldn't be necessary if only we could catch
exceptions in expressions...

scripts/csv.py

@@ -1296,11 +1296,11 @@ def punescape(s, attrs=None):
             f = m.group('format')
             if f[-1] in 'dboxX':
                 if isinstance(v, str):
-                    v = try_dat(v) or 0
+                    v = dat(v, 0)
                 v = int(v)
             elif f[-1] in 'fFeEgG':
                 if isinstance(v, str):
-                    v = try_dat(v) or 0
+                    v = dat(v, 0)
                 v = float(v)
             else:
                 f = ('<' if '-' in f else '>') + f.replace('-', '')