Add man function to promote fish's man pages so it can serve as a suitable replacement for help

share/functions/man.fish

@@ -0,0 +1,21 @@
+function man --description "Format and display the on-line manual pages"
+	# Work around OS X's "builtin" manpage that everything symlinks to,
+	# by prepending our fish datadir to man. This also ensures that man gives fish's
+	# man pages priority, without having to put fish's bin directories first in $PATH
+	# Temporarily set a MANPATH, unless one is set already
+	if not set -q MANPATH
+		set -l fish_manpath (dirname $__fish_datadir)/fish/man
+		if test -d "$fish_manpath"
+			# Notice local but exported variable
+			set -lx MANPATH "$fish_manpath":(command man --path)
+			
+			# Invoke man with this manpath, and we're done
+			command man $argv
+			return
+		end
+	end
+	
+	# If MANPATH is set explicitly, or fish's man pages could not be found,
+	# just invoke man normally
+	command man $argv
+end