Who is Maester Aemon (Targaryen) from A Feast for Crows and what is their importance?

Aemon Targaryen is the next in line to be king. He gave up in place in line to join the Citadel, where he could learn to be a maester. When Aemon dies at one hundred two, he was believed to be the last living Dragon. The Citadel sent him off to the Wall instead of making him an Archmaester simply because he was a Dragon. The world that the Citadel is building has no room for magic, dragons, or sorcerers. Master Aemon realizes the meaning of a vital prophesy just before his death, and sends Sam to the Citadel to tell of it. Aemon is not the last of the Dragons.