By Michele Kambas NICOSIA (Reuters) - Leaders of rival communities in ethnically-split Cyprus shared coffee and cake on Saturday in a symbolic gesture underscoring a thaw in relations over a conflict spanning decades. Cypriot President Nicos Anastasiades, the Greek Cypriot leader, and Turkish Cypriot leader Mustafa Akinci spent more than an hour strolling through medieval streets of Nicosia, a first in the history of the Cyprus dispute. "This is a historic day," Akinci told reporters, clapping wellwishers as he and Anastasiades walked across a United Nations-monitored 'green line' keeping Greek and Turkish Cypriots apart.