[BUG] does not accept proper pairix format

[esrice]

Describe the bug
When giving pre a file in pairix format, it fails to parse the file and throws an exception. To make it accept pairix format, you have to remove some header lines that it does not expect, despite these header lines being officially part of the pairix specification.

To Reproduce
Steps to reproduce the behavior:

1. Find a valid pairix format file, containing header lines starting with ## pairs, #shape, #chromsize, and #columns, as specified in https://github.com/4dn-dcic/pairix/blob/master/pairs_format_specification.md
2. Run hic_tools pre with this file as input:

java -Xmx36G -jar /path/to/hic_tools.jar pairix_file.pairs outfile.hic chrom.sizes

This results in the following error:

java.lang.ArrayIndexOutOfBoundsException: 3
        at hic.tools.utils.iterators.mnd.ComplexLineParser.generateBasicPair(ComplexLineParser.java:56)
        at hic.tools.utils.iterators.mnd.MNDFileParser.parseDCICFormat(MNDFileParser.java:118)
        at hic.tools.utils.iterators.mnd.MNDFileParser.parse(MNDFileParser.java:83)
        at hic.tools.utils.iterators.mnd.GenericPairIterator.advance(GenericPairIterator.java:56)
        at hic.tools.utils.iterators.mnd.GenericPairIterator.next(GenericPairIterator.java:46)
        at hic.tools.utils.original.Preprocessor.computeWholeGenomeMatrix(Preprocessor.java:88)
        at hic.tools.utils.original.Preprocessor.writeBody(Preprocessor.java:114)
        at hic.tools.utils.original.Preprocessor.preprocess(Preprocessor.java:54)
        at hic.tools.clt.old.PreProcessing.run(PreProcessing.java:149)
        at hic.tools.HiCTools.main(HiCTools.java:83)

It appears to be trying to parse one of the header lines as if it is not a header line. To fix, I removed all header lines except those starting with ## pairs and #columns and it worked fine.

Expected behavior
The program should not crash on validly-formatted pairix format input.