Fixed bug #2: "5s should round up, not down".

Improved Read instance to only return a single value for "reads".
Merge branch 'master' of https://github.com/PaulJohnson/Haskell-Decimal.git
Fixed some warning messages.
Fixed documentation.
More doc fixes.
Added test for fromRational with DecimalRaw Int
Added test case for DecimalConvert with overflow.
Fixed divRound to round 0.5 away from zero.