Enhanced return value from asset.plugins to be a first-class
object (PluginSet) that has aggregate plugin operation methods
PluginSet.handle and PluginSet.filter.
v0.6.7
Added initial implementation of asset.plugin helper decorator
v0.6.6
Corrected regex negative handling
v0.6.5
Updated asset.plugins to support loading of unregistered plugins
Changed '!' asset.plugins prefix to '-'
v0.6.4
Added asset.plugins plugin loading mechanism that supports simple
ordering and overriding of plugins
v0.6.3
Added check for egg vs. not-egg in unit tests
v0.6.2
Removed distribute dependency (thanks jlec)
v0.6.1
Added Python 3 support
v0.6
Added more standard file object compatibility (stream iteration,
reading with size, and closing)