Switch to new API - close #8

The new API is more C-like and will allow consistency across all future
supported language targets.

spec/test_lexer_result_value.d

@@ -9,12 +9,13 @@ int main()
 unittest
 {
     string input = `x`;
-    auto parser = new Parser(input);
-    assert(parser.parse() == P_SUCCESS);
-    assert(parser.result == 1u);
+    p_context_t context;
+    p_context_init(&context, input);
+    assert(p_parse(&context) == P_SUCCESS);
+    assert(p_result(&context) == 1u);
 
     input = `fabulous`;
-    parser = new Parser(input);
-    assert(parser.parse() == P_SUCCESS);
-    assert(parser.result == 8u);
+    p_context_init(&context, input);
+    assert(p_parse(&context) == P_SUCCESS);
+    assert(p_result(&context) == 8u);
 }