By Krystal Hu (Reuters) – Citigroup has poached three veteran tech bankers from Credit Suisse Group AG and Barclays, as it doubles down on expanding the software franchise, according to memos seen by Reuters on Tuesday. Dan McDow, who led global software investment banking at Credit Suisse, left the Swiss lender after 16 years. Based in New York, he will co-run the global software investment banking unit at Citi with Niall Cannon and Brian Marshall. McDow will specialize in the applications segment, while Niall and Brian continue to focus on cybersecurity and infrastructure, according to the m…