William Wallace would not be happy.  Shares of the Royal Bank of Scotland lost almost exactly two-thirds of their value today after the company warned that it might report the biggest ever yearly loss in UK corporate history. Here's how RBS, as it's known, was brought to its knees.  Simon Kennedy writes, "Like other U.K. banks, RBS has been hit hard by write-downs on risky assets, the virtual closure of wholesale lending markets and rising charges to cover customers who can't ...