Support for Ctrl-C cancellation in new parser. Added tests for it too.

parser.h

@@ -287,6 +287,9 @@ class parser_t
     /** Position of last error */
     int err_pos;
     
+    /** Indication that we should skip all blocks */
+    bool cancellation_requested;
+    
     /** Stack of execution contexts. We own these pointers and must delete them */
     std::vector<parse_execution_context_t *> execution_contexts;