implementing native Windows, node-module add-on to support recursive file watching
corrections per code review
per code review, using STL classes.  sharing data with thread by value.  various refactoring and cleanup
minor tweak to cleanup unused constant
fix cleanup issues identified over code review
per code review, guarding against repeated Startup() calls and failed i/o completion ports
reformatting inline ctor/dtor code for better maintainability
per code review, removing unnecessary pointer check
per code review, adding null pointer checks within the callbacks, just in case
fixed improper thread termination as a result of previous commit
Merge pull request #6686 from adobe/jeff/filewatcher-fixes-windows

Implement node-module add-on for native Windows file watching