Port to Isabelle 2019.

.ci/Jenkinsfile

@@ -3,7 +3,7 @@ pipeline {
     stages {
         stage('Build') {
             steps {
-                sh 'docker run -v $PWD/:/WORKING logicalhacking:isabelle2018 isabelle build -D /WORKING'
+                sh 'docker run -v $PWD/:/WORKING logicalhacking:isabelle2019 isabelle build -D /WORKING'
             }
         }
     }

Assert.thy

@@ -1,5 +1,5 @@
 (***********************************************************************************
- * Copyright (c) 2018 Achim D. Brucker
+ * Copyright (c) 2018-2019 Achim D. Brucker
  *
  * All rights reserved.
  *

Hiding_Type_Variables.thy

@@ -1,5 +1,5 @@
 (***********************************************************************************
- * Copyright (c) 2018 Achim D. Brucker
+ * Copyright (c) 2018-2019 Achim D. Brucker
  *
  * All rights reserved.
  *

README.md

@@ -5,7 +5,7 @@ functionality to [Isabelle](https://isabelle.in.tum.de) or showcase
 specific functionality. The individual hacks usually consist out of 
 a single theory file and all documentation is contained in that 
 theory file. The master branch should work with the latest official 
-release of Isabelle (Isabelle 2018, at time of writing), hacks for 
+release of Isabelle (Isabelle 2019, at time of writing), hacks for 
 older versions might be available on a dedicated branch.
 
 ## List of Isabelle Hacks

document/root.tex

@@ -67,7 +67,7 @@
       specific functionality. The individual hacks usually consist out of 
       a single theory file and all documentation is contained in that 
       theory file. The master branch should work with the latest official 
-      release of Isabelle (Isabelle 2018, at time of writing), hacks for 
+      release of Isabelle (Isabelle 2019, at time of writing), hacks for 
       older versions might be available on a dedicated branch.
 
     %\bigskip