Parser: raise corpus parse rate from 57% to 69%

Grammar gains: array types, directive flags, declaration-level directive
modifiers, parameter markers, backticked declaration names, notes after a
block-valued declaration, 'if cond then stmt', 'ifx c else v', '#module_parameters'
two-group form, '(.*)' prefix dereference, and '#asm' bodies consumed opaquely
(they are x86-64 assembly, not Jai).

Return items no longer take a default value: allowing one made
'f: (K) -> u32 = null' swallow the enclosing parameter's default and read the
rest of the parameter list as extra return values.

src/main/gen/dev/hgh/jai/psi/impl/JaiDerefCastExprImpl.java

@@ -0,0 +1,36 @@
+// This is a generated file. Not intended for manual editing.
+package dev.hgh.jai.psi.impl;
+
+import java.util.List;
+import org.jetbrains.annotations.*;
+import com.intellij.lang.ASTNode;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiElementVisitor;
+import com.intellij.psi.util.PsiTreeUtil;
+import static dev.hgh.jai.psi.JaiTypes.*;
+import dev.hgh.jai.psi.*;
+
+public class JaiDerefCastExprImpl extends JaiExprImpl implements JaiDerefCastExpr {
+
+  public JaiDerefCastExprImpl(@NotNull ASTNode node) {
+    super(node);
+  }
+
+  @Override
+  public void accept(@NotNull JaiVisitor visitor) {
+    visitor.visitDerefCastExpr(this);
+  }
+
+  @Override
+  public void accept(@NotNull PsiElementVisitor visitor) {
+    if (visitor instanceof JaiVisitor) accept((JaiVisitor)visitor);
+    else super.accept(visitor);
+  }
+
+  @Override
+  @Nullable
+  public JaiExpr getExpr() {
+    return findChildByClass(JaiExpr.class);
+  }
+
+}