Seven months after he resigned the presidency of the Czechoslovak federation to protest its disintegration, Vaclav Havel is a President once more. Elected to a five-year term by the parliament of the four-week-old Czech Republic, Havel will preside from the same office in Prague's Hradcany Castle over about two-thirds of his former country. The onetime playwright and erstwhile communist-era dissident promised to maintain a "moral dimension" in his government and to serve as a "more experienced and wiser" statesman in promoting accord with his nation's new neighbor, Slovakia.