Bug 798313 - "File/Import/Import Transactions From CSV" crashes Gnucash.

Don't shutdown and re-initialize the expression parser after every parse,
doing so overflows the Guile garbage collector's memory-region array.

It also forces the expression parser to load the user expressions-2.0
for every parse which is extremely expensive.

gnucash/import-export/csv-imp/gnc-imp-props-tx.cpp

@@ -223,7 +223,6 @@ static GncNumeric parse_price (const std::string &str)
     char *endptr;
 
     auto success = gnc_exp_parser_parse (str.c_str(), &val, &endptr);
-    gnc_exp_parser_shutdown();
     if (!success)
         throw std::invalid_argument (_("Price can't be parsed into a number."));