The default so far was 0, which meant there would be no significant
digits at all, yielding results that looked strange/wrong to the user.
Long-term all remaining drivers should be fixed to use the actual,
correct digits and spec_digits values according to the device's
capabilities and/or datasheet/manual. Until that is done, a default
of digits=2 is used as a temporary workaround.
This fixes the remaining parts of bug #815.
Since Autoconf places some important feature flags only into the
configuration header, it is necessary to include it globally to
guarantee a consistent build.
A few of these were pretty serious, like missing arguments,
passing integers where a string was expected, and so on.
In some places, change the types used by the code rather than
just the format strings.