Added alkane matching by CAS or IUPAC name

[Mailaender]

This is much smarter for cases where there are already fully identified chromatograms.

[eselmeister]

For a simple access of the RetentionIndexCalculator, I would recommend to keep the old method

public static int getAlkaneNumber(String name) {...}

and rename the new method e.g. to

public static int getAlkaneNumberEnhanced(ILibraryInformation libraryInformation) {...}

[Mailaender]

Updated it to not break API.