Display Unix man pages inside Atom. This has been tested with OSX. It probably needs work for Linux. It is not applicable to Windows. (Or do we want to display Cygwin man pages on Windows?)
There is a "Man: Man" command in the command palette. It asks for the man page to view.
To learn how grammars work, see here:
Good catch. Let us know what about this package looks wrong to you, and we'll investigate right away.