Unnecessary boxing of IndexOptions enum

[theolivenbaum]

Found another easy improvement:

There are plenty of calls to IndexOptions.CompareTo(IndexOptions.DOCS_AND_FREQS_AND_POSITIONS) in the code, such as this one:

if (outerInstance.fieldInfo.IndexOptions.CompareTo(IndexOptions.DOCS_AND_FREQS_AND_POSITIONS) < 0)
{
    // Positions were not indexed:
    return null;
}

The problem is that CompareTo receives an object, which leads to boxing the enum:

[theolivenbaum]

From a quick glance, this seems to be only happening for the IndexOptions enum: