Switch to 11 build target / source on javac.

Minor bit of cleanup in the ant scripts around the build src and target on javac, enabling use of Java 11 language features within processing itself. Note that the build is sustained on either 1.8 or 11 in terms of lanugage features but the code is no longer compatible with the Java 8 runtime due to backwards-incompatable changes made starting in Java 9.

java/libraries/dxf/build.xml

@@ -13,8 +13,8 @@
     <fail unless="core-built" message="Please build the core library first and make sure it sits in ../../../core/library/core.jar" />
 
     <mkdir dir="bin" />
-    <javac source="1.8"
-	   target="1.8"
+    <javac source="11"
+	   target="11"
 	   srcdir="src" destdir="bin"
 	   encoding="UTF-8"
 	   includeAntRuntime="false"

java/libraries/io/build.xml

@@ -1,31 +1,31 @@
 <?xml version="1.0"?>
 <project name="Processing Hardware I/O Library" default="build">
-  
+
   <target name="clean" description="Clean the build directories">
     <delete dir="bin" />
     <delete file="library/io.jar" />
   </target>
-  
+
   <target name="compile" description="Compile sources">
     <condition property="core-built">
       <available file="../../../core/library/core.jar" />
     </condition>
     <fail unless="core-built" message="Please build the core library first and make sure it sits in ../../../core/library/core.jar" />
-    
+
     <mkdir dir="bin" />
-    <javac source="1.8"
-	   target="1.8"
-	   srcdir="src" destdir="bin" 
+    <javac source="11"
+	   target="11"
+	   srcdir="src" destdir="bin"
 	   encoding="UTF-8"
 	   includeAntRuntime="false"
 	   classpath="../../../core/library/core.jar"
 	   nowarn="true"
 	   compiler="org.eclipse.jdt.core.JDTCompilerAdapter">
-      <compilerclasspath path="../../mode/org.eclipse.jdt.core.jar; 
+      <compilerclasspath path="../../mode/org.eclipse.jdt.core.jar;
                                ../../mode/jdtCompilerAdapter.jar" />
     </javac>
   </target>
-  
+
   <target name="build" depends="compile" description="Build I/O library">
     <jar basedir="bin" destfile="library/io.jar" />
   </target>

java/libraries/net/build.xml

@@ -13,8 +13,8 @@
     <fail unless="core-built" message="Please build the core library first and make sure it sits in ../../../core/library/core.jar" />
 
     <mkdir dir="bin" />
-    <javac source="1.8"
-	   target="1.8"
+    <javac source="11"
+	   target="11"
 	   srcdir="src" destdir="bin"
 	   encoding="UTF-8"
 	   includeAntRuntime="false"

java/libraries/pdf/build.xml

@@ -13,8 +13,8 @@
     <fail unless="core-built" message="Please build the core library first and make sure it sits in ../../../core/library/core.jar" />
 
     <mkdir dir="bin" />
-    <javac source="1.8"
-	   target="1.8"
+    <javac source="11"
+	   target="11"
 	   srcdir="src" destdir="bin"
 	   encoding="UTF-8"
 	   includeAntRuntime="false"

java/libraries/serial/build.xml

@@ -13,8 +13,8 @@
     <fail unless="core-built" message="Please build the core library first and make sure it sits in ../../../core/library/core.jar" />
 
     <mkdir dir="bin" />
-    <javac source="1.8"
-	   target="1.8"
+    <javac source="11"
+	   target="11"
 	   srcdir="src" destdir="bin"
 	   encoding="UTF-8"
 	   includeAntRuntime="false"

java/libraries/svg/build.xml

@@ -13,8 +13,8 @@
     <fail unless="core-built" message="Please build the core library first and make sure it sits in ../../../core/library/core.jar" />
 
     <mkdir dir="bin" />
-    <javac source="1.8"
-	   target="1.8"
+    <javac source="11"
+	   target="11"
 	   srcdir="src" destdir="bin"
 	   encoding="UTF-8"
 	   includeAntRuntime="false"