Check if event is just an attrib flag that can be skipped

Recently on Sublime Text 3 / OS X 10.9.3 and Go 1.2.2, I've found that just switching between tabs in my editor would trigger a ```MODIFY|ATTIB``` event and rebuild my application each time. It's obviously sending some attribute update, perhaps OSX saying it's been "touched" by the user and dispatching this through. In any case, I've fixed this by testing if ```ev``` is an attribute (metadata) flag and just skipping it.