Filter Abstraction (#25)

* Add category, back filters by dictionary

* Complete internal filter set

* Fix AreaSize filter

* Populate filter object the hard way

* Manipulation flags should not be filters

* None of them need to be public

* Convert to partial helper method

* Better method use

* Field, not string; no dictionary

* Add FilterTo method for later

* More naming options (easier conversion)

* Update README

SabreTools.Library/Data/Enums.cs

@@ -261,7 +261,6 @@
         Game,
     }
 
-
     /// <summary>
     /// Determines the DAT deduplication type
     /// </summary>
@@ -351,6 +350,7 @@
         NULL = 0,
 
         // Generic DatItem
+        ItemType,
         Name,
         PartName,
         PartInterface,
@@ -365,6 +365,7 @@
         Year,
         Manufacturer,
         Publisher,
+        Category,
         RomOf,
         CloneOf,
         SampleOf,