2.05
     -- slightly more robust pipeline
     -- gulp.  Productions still weren't terminating the pipeline
        in all cases.

2.04
     -- better documentation
     -- added test case for passing the store down to nested
        pipelines.  Fixed the bug too!

2.03
     -- everything inherits from Pipeline::Base now 
     -- added Pipeline::Store::ISA to the distribution

2.02
     -- fixed bug with Pipeline::Productions not terminating the
     	pipeline.  This was a very silly bug to have.

2.01 
     -- can now request a copy of the store from Pipeline::Store::Simple
     -- added debug() and emit() methods to Pipeline::Segment