Bump version to 2.1.9

- Substitute occurrences of "2.1.8" with "2.1.9" using:
  git grep -I -l -e '2\.1\.8' | xargs \
  sed -b -i -e 's/2\.1\.8/2\.1\.9/g'

CUETools.CTDB.EACPlugin/Plugin.cs

@@ -61,7 +61,7 @@ namespace AudioDataPlugIn
         // the plugin and for display in the log file
         public string GetAudioTransferPluginName()
         {
-            return "CUETools DB Plugin V2.1.8";
+            return "CUETools DB Plugin V2.1.9";
         }
 
         // Each plugin should have its own options page.
@@ -278,7 +278,7 @@ namespace AudioDataPlugIn
 #endif
                 var form = new FormSubmitParity(
                     ctdb,
-                    "EAC" + m_data.HostVersion + " CTDB 2.1.8",
+                    "EAC" + m_data.HostVersion + " CTDB 2.1.9",
                     m_drivename,
                     conf,
                     (arTest.Position != 0 && arTest.CRC32(0) == ar.CRC32(0)) ? 100 :