Removed the 'needsstorage' thing from Dsymbol. Arguments are not always given storage when applicable. This is not longer treat specially

in this regard. Code for accessing nested variables and contexts rewritten. Probably more. Fairly well tested.

gen/dvalue.h

@@ -27,7 +27,6 @@ struct DConstValue;
 struct DNullValue;
 struct DVarValue;
 struct DFieldValue;
-struct DThisValue;
 struct DFuncValue;
 struct DSliceValue;
 struct DArrayLenValue;
@@ -49,7 +48,6 @@ struct DValue : Object
     virtual DNullValue* isNull() { return NULL; }
     virtual DVarValue* isVar() { return NULL; }
     virtual DFieldValue* isField() { return NULL; }
-    virtual DThisValue* isThis() { return NULL; }
     virtual DSliceValue* isSlice() { return NULL; }
     virtual DFuncValue* isFunc() { return NULL; }
     virtual DArrayLenValue* isArrayLen() { return NULL; }
@@ -130,13 +128,6 @@ struct DFieldValue : DVarValue
     virtual DFieldValue* isField() { return this; }
 };
 
-// this d-value
-struct DThisValue : DVarValue
-{
-    DThisValue(Type* t, VarDeclaration* vd, LLValue* llvmValue) : DVarValue(t, vd, llvmValue, true) {}
-    virtual DThisValue* isThis() { return this; }
-};
-
 // slice d-value
 struct DSliceValue : DValue
 {