Use a consistent Ord instance for BigFloat, other minor fixes.

[orlitzky]

• Add a custom Ord instance for BigFloat with compare based on toRational.
• Add two QuickCheck properties for BigFloat, a test suite, and corresponding cabal stanza.
• Remove trailing whitespace everywhere.
• Convert tabs to spaces everywhere.
• Manually undefine a few missing RealFloat functions.
• Add some GHC warnings (untriggered) to the cabal file for later QA.
• Replace all GHC option flags, e.g. -fglasgow-exts, with LANGUAGE pragmas.
• Add a missing type signature in FixedFunctions.hs.
• Remove an unused debug import in Symbolic.hs.

[DanBurton]

I've merged it, but I don't like the new dependencies on QuickCheck & friends for building the library. I'm going to separate the library from the test code so that people can install just the library without the additional dependencies.

[orlitzky]

Thanks, I don't like them either, but I've asked around and the three options seem to be,

1. Put the tests in the module with the code. Allows testing of internal functions, but requires the test libs to build.
2. Put the tests in a separate module. Doesn't require test libs to build, but you have to export everything you want to test.
3. Use the preprocessor to export everything when testing. Unspeakably ugly.

I tend to prefer (1), but the benefits don't exist until someone writes some internal tests, so do whatever =)

[DanBurton]

The reason I chose Option 2 for this package is because it's not really mine, and I didn't want to force the extra dependencies on users of the package. Option 3 doesn't seem that bad to me; you can just export the extra things you want to test. Option 1 isn't all that bad, but personally I'd avoid doing it until all of the testing dependencies are in the Haskell Platform (right now only quick check is, iinm). Dependency hell is not fun.