Moved in a separated class the methods that are related to the string representation of IEEE 754 values.
Those methods are not really "mathematic", and some more are going to be added. Having a separated class
for them also clarify method and constant names (e.g. it is not clearer that DecimalFunctions.fractionDigitsForValue
is about the fraction digits of the decimal representation of a IEEE 754 double).


git-svn-id: https://svn.apache.org/repos/asf/sis/branches/JDK7@1538105 13f79535-47bb-0310-9956-ffa450edef68