WIP on auth system
little web app for testing cookie-based credential operations
give all Components a this.serialNumber
make Alignments track type an alias for alignments2
bugfix to GFF3 parser comment parsing
bugfix to new Util.loadJS
make new configuration system check for any slots that are unset but marked `required`
fix test app byte-range serving
add JBrowse/Util/DeferredGenerator, an asynchronous ggenerator that brings many of the benefits of dojo/Deferred to iterating
improve DeferredGenerator tests
change DeferredGenerator API to have .each for iterating callbacks, and have .then be only for ending callbacks
add Transport-aware JBrowse/Model/Resource/* to replace JBrowse/Model/*Blob classes, flesh out Resource and Transport-choosing logic.  port BAM store to use Resources and Transports
require authentication in test webapp for file fetching
remove some unused functions from JBrowse/Util
tweak track error message display wording
auth API starting to work
add support for `requestTechnique` param in HTTP transport driver, allowing iframe and script requests
delete nonworking  _Cookie.js credentialslot class
make a JBrowse/Transport/_RequestBased abstract base class to make the Transport abstraction less leaky, so that WebSockets could eventually fit cleanly into the Transport paradigm
modify testapp_1.pl to run at /testapp1, behind a reverse-proxy