exposurses

Also: More evidence I am in a continual half-daze

- Need to define shutter value as double in `aperture` as otherwise both
arguments will be integers and I'm guessing it'd not going to work out
well. Plus... need to use `fraction_to_double` anyway to feed the
value in.
- Had done the "substring" thing wrong in `strncpy` and was one decimal
place off in getting the paerture value. I.e. would have got "1."
instead of "1.4" from "f/1.4"
- Like the fool I am, in the loop and the copy and paste I'd done, I'd
not changed from `aperture_array[0]` to `aperture_array[n]` check-in: 845d8653eb user: base@atomicules.co.uk tags: origin/master, trunk

See this commit: 8d3e66b5ecffa8bcf7691c3f0600840b934beb1a

I'm such an idiot.

- Remove `set_top_row` when setting the shutter menu to the correct
value. Leaving this in fooled me into thinking I had things working
because I just happened to test on the matching ISO/Aperture values.
Plonker. And then it turns out, there was loads wrong.
- Need to include stdlib.h for `strtod` function, otherwise it uses some
kind of stub function (no complaints in compile or use, but it just
doesn't work).
- Wasn't passing right kind of values to `shutter` anyway! Need to
convert these to numeric
- Need to use `fabs` not `abs` for doubles.
- In `nearest_match` wasn't using the correct arrays, had copied over
`iso_array` and forgotten to change them
- Use `strstr` instead `strchr` as couldn't get the former to work and
was probably the wrong one to be using
- Leave some commented out stuff at the bottom that I've been using for
debugging
- check-in: 68919dca22 user: base@atomicules.co.uk tags: origin/master, trunk