Add Support to stringtools for detecting BOM

[Sqeaky]

Some Unicode text files have a Byte Order Mark at the beginning of the file. This is usually 4 bytes that indicate if the file was made on a big or little endian machines. The JagatiIndex.cmake file has one that can be used as an Example. Having at least 4 functions on the StringTools seems like a good idea: IsBigEndianBOM(String), isLittleEndingBOM(String), IsBom(String), IsBOMDigit(Character).