Remove .NET Framework 4.6.2/4.7.2 (#24)

* Remove < .NET 4.8, general cleanup

* Abstract

* Tango

* Banner

* Scan no more

* Common

* Application

* Access

* Filter-feeder

* Graffiti

* Paint-over

* Law and Order

* XOR-o

* Unused staircase

* Maybe

* Maybe not

* Delete this

* The word is "no"

* Emit

* Improper

* Aye aye

* Fence

* Barrier

* Monkey

* Pail

* Lines

SabreTools.Library/DatItems/Archive.cs

@@ -54,10 +54,8 @@ namespace SabreTools.Library.DatItems
                 Devices = this.Devices,
                 MachineType = this.MachineType,
 
-                SystemID = this.SystemID,
-                System = this.System,
-                SourceID = this.SourceID,
-                Source = this.Source,
+                IndexId = this.IndexId,
+                IndexSource = this.IndexSource,
             };
         }