AMSTERDAM (Reuters) -Dutch Crown Princess Catharina-Amalia is under heightened security due to concern that she could be targeted by criminals, Dutch news agency ANP reported on Thursday, citing her parents. “She can hardly leave the house,” ANP quoted Queen Maxima as saying during a state visit to Sweden with her husband King Willem-Alexander. Amalia, 18, heir to the Dutch throne, began studying at the University of Amsterdam last month and had moved into an apartment in Amsterdam, but the royal couple now said concerns for her safety have forced her to move back to Huis ten Bosch royal palac…