preview of api change with error support in AssetPackTrace
Adding hop
Merge pull request #19 from financeCoding/add_hop

Adding hop
trace: inject tracer into loaders and importers
define some type of AssetPackTraceEvent as const
tracer: include in loader test
+ move AssetLoadEnd call before completer.complete(x) to available in tracer.events when expected
tracer: include in import test
+ fix a bug in const of AssetPackEvent
Merge https://github.com/johnmccutchan/asset_pack into error_on_load
tracer is optional in manager configuration
fix a wrong trace ImportEnd in PackImporter
trace: try to be more be more informative about some import error
wrap at 80 columns
fix typo made during wrapping
add a "manual" test of AssetPackTrace.toTraceViewer(),
testpack.trace is a sample loadable in chrome://tracing
instance of AssetPackTrace can monitor several pack (seq and concurrently)
AssetPackTrace: refactor (remove useless, factorize code)
remove commented code in test of trace_viewer (tried to store in local file)
refactor: move methods 'toTraceViewer' into AssetPackTraceViewer
gitignore *.dart.js*
Merge pull request #17 from davidB/error_on_load

notification of error in loaders, importers