GenomicAnnotations.jl

Updated to the new (v0.20) DataFrames API.
Fixed a bug when reading files with empty lines.

Updated for DataFrames v0.19.0.

Some updates:

• Added GZip.jl as a dependency, and updated readgbk to read gzipped files.
• Allowed parsing of loci with "^" in the position string
• Added special cases to @genes.
  • iscds expands to :feature == "CDS"
  • get(s::Symbol, default) expands to get(gene, s, default)
  • When providing just a symbol (such as in @genes(chr, :pseudo)), missings will be treated as falses.