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/JaiDeclNames.java

@@ -7,4 +7,7 @@ import com.intellij.psi.PsiElement;
 
 public interface JaiDeclNames extends PsiElement {
 
+  @NotNull
+  List<JaiDeclName> getDeclNameList();
+
 }