CHANGES IN VERSION 1.15
-----------------------

NEW FEATURES

    o Integrated with tabix via Rsamtools. BED and GFF export methods
      now generate a tabix index, if index=TRUE. Most import() methods
      gain a 'which' argument that takes advantage of tabix, when
      available.
      
    o Added wigToBigWig() function for efficient conversion of WIG to BigWig.
    
    o Added SeqinfoForBSGenome() and SeqinfoForUCSCGenome() for
      conveniently retrieving Seqinfo objects for a given genome.
    
    o Added support for FASTA import/export via Biostrings.

    o GTF and GVF files are now parsed as GFF.

SIGNIFICANT USER-VISIBLE CHANGES

    o The import/export API is now based on RTLFile objects, which
      wrap a file path, URL or connection. There is an RTLFile
      subclass for every file format. This makes it easier to extend
      rtracklayer (export, import) with new file types. The existing
      API is still supported (and even encouraged for most uses).

    o Handle CSV attributes in GFF3 using CharacterList columns.

    o BED columns thickStart/thickEnd translate to an IRanges column
      named "thick". The blockStarts/Sizes/Count columns now map to a
      single RangesList "blocks" column.
    
BUG FIXES

    o Numerous fixes in the import/export methods, as a result of
      implementing a full unit test suite. If something was not
      working for you in the past, please try again.

    o Compression and connections should now work fairly uniformly
      across file types.

(start date: 29 March, 2012)
