Gene info parser fix

[SRodenburg]

I ran into some problems while building a hg38 seed database:

Sometimes the file Homo_sapiens.gene_info contains missing values in the map_location and/or chromosome columns. This file is downloaded from NCBI and required when updating genes and gene aliases.
Additionally, sometimes a particular symbol from the GenCode annotation file is not in the info file, causing a NullPointerException.

Changes:

• When the chromosome can't be parsed from the map_location column, try the chromosome column. If that also fails, skip gene.
• prevent NullPointerException when the gene symbol can't be found, and instead showing a warning, and skipping the gene.

[khzhu]

combine two ifs into one, so the second condition will not be evaluated if first one is false.

       if (chr.equals("-") && (!parts[6].equals("-")) {
              chr = parts[6];
       } else {
              // skip line if still unable to parse chr
             continue;
      }

[SRodenburg]

The unittests revealed a problem with your proposed implementation; the code will go straight to continue when chr does not equal "-", which is obviously not what we want.

A "synonymous" implementation would be:

if (chr.equals("-") && parts[6].equals("-")) {
    continue
} 
if (chr.equals("-")) {
    chr = parts[6];
}

However, this requires 2 logical tests while my original implemetation for most of the lines requires 1, thus would be better performance-wise.

[SRodenburg]

@inodb can you merge?