visor.Visor.GetSignedBlocksSince does not return genesis block

[isaacvr]

Sometimes it is necessary to fetch genesis block from high level code. For example, working on skycoin/services#12, I need to extract genesis block of new coin and create unspent outputs with coin.CreateUnspent to send initial volume to distribution addresses.

However visor.Visor.GetSignedBlocksSince(seq=0, ct=1) always returns empty slice, because (seq=0 and ct > 0) is an edge case.

Also docs for daemon.Visor.GetSignedBlocks claim that it "returns numbers of signed blocks since seq". However docs for visor.Visor.GetSignedBlocks metntion that it "returns N signed blocks more recent than Seq"