Simplify some code
Update spec for plugin combo
Rebuild packages
Reduce memery taken. close #782
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Little tweaking
Add test specs for loading duplicated ids
Rebuild packages
Rebuild packages
Add resolveCache to support config changing dynamically
Remove support for changing condig dynamically
Fix a bug for top-level id
Remove module._resolveCache
Rebuild packages
Add requested event for combo plugin to clean up memory usage
Rebuild packages
Change data structure of comboHash object
Rebuild plugins
DO NOT tweak performance for rare case
Rebuild packages