d: remove unnecessary methods from the Lexer interface

The complete symbol approach in yylex removes the need for the methods
semanticVal, startPos and endPos, which were used when the values were
reported separately.

* data/skeletons/lalr1.d: Here.
* doc/bison.texi: Remove sections about the three methods.
* examples/d/calc/calc.y, examples/d/simple/calc.y: Remove the unused methods.
* tests/calc.at, tests/d.at, tests/scanner.at: Test it.

examples/d/calc/calc.y

@@ -108,11 +108,6 @@ if (isInputRange!R && is(ElementType!R : dchar))
 
   Value semanticVal_;
 
-  public final Value semanticVal()
-  {
-    return semanticVal_;
-  }
-
   Symbol yylex()
   {
     import std.uni : isWhite, isNumber;
@@ -167,16 +162,6 @@ if (isInputRange!R && is(ElementType!R : dchar))
       default: assert(0);
     }
   }
-
-  Position startPos() const
-  {
-    return location.begin;
-  }
-
-  Position endPos() const
-  {
-    return location.end;
-  }
 }
 
 int main()