[matlab] Add Filter enum class

Author: mpsonntag

+nix/Filter.m

@@ -0,0 +1,14 @@
+classdef Filter < uint8
+    %FILTER available nix custom filters
+
+    enumeration
+        accept_all (0); % requires an empty value
+        id (1);
+        ids (2); % requires a cell array
+        type (3);
+        name (4);
+        metadata (5);
+        source (6);
+    end
+    
+end