Fix generator and add tests (#85)

* Fixed problem where generated shaders were not being given versions.

* Fixed image and reducer tests and re-worked obfuscator.

ast/src/main/java/com/graphicsfuzz/common/ast/TranslationUnit.java

@@ -36,7 +36,7 @@
 public class TranslationUnit implements IAstNode {
 
   private final ShaderKind shaderKind;
-  private final Optional<ShadingLanguageVersion> shadingLanguageVersion;
+  private Optional<ShadingLanguageVersion> shadingLanguageVersion;
   private List<Declaration> topLevelDeclarations;
 
   /**
@@ -80,6 +80,10 @@ public ShadingLanguageVersion getShadingLanguageVersion() {
     return shadingLanguageVersion.get();
   }
 
+  public void setShadingLanguageVersion(ShadingLanguageVersion shadingLanguageVersion) {
+    this.shadingLanguageVersion = Optional.of(shadingLanguageVersion);
+  }
+
   public void setTopLevelDeclarations(List<Declaration> topLevelDeclarations) {
     this.topLevelDeclarations = topLevelDeclarations;
   }

ast/src/main/java/com/graphicsfuzz/common/util/ParseHelper.java

@@ -65,6 +65,12 @@ public static synchronized TranslationUnit parse(File file)
         ShaderKind.fromExtension(FilenameUtils.getExtension(file.getName())));
   }
 
+  public static synchronized TranslationUnit parse(String string, ShaderKind shaderKind)
+      throws IOException, ParseTimeoutException {
+    return parseInputStream(new ByteArrayInputStream(string.getBytes(StandardCharsets.UTF_8)),
+        shaderKind);
+  }
+
   /**
    * Parses a shader from a given string.  The shader is assumed to be a fragment shader;
    * typically the shader kind is unimportant when we parse from strings.
@@ -75,8 +81,7 @@ public static synchronized TranslationUnit parse(File file)
    */
   public static synchronized TranslationUnit parse(String string)
         throws IOException, ParseTimeoutException {
-    return parseInputStream(new ByteArrayInputStream(string.getBytes(StandardCharsets.UTF_8)),
-        ShaderKind.FRAGMENT);
+    return parse(string, ShaderKind.FRAGMENT);
   }
 
   private static synchronized TranslationUnit parseInputStream(InputStream input,