cmd/geth, cmd/utils, core, rpc: renamed to blockchain

* Renamed ChainManager to BlockChain
* Checkpointing is no longer required and never really properly worked
when the state was corrupted.

core/vm/contract.go

@@ -118,8 +118,8 @@ func (self *Contract) SetCode(code []byte) {
 	self.Code = code
 }
 
-// SetCallCode sets the address of the code address and sets the code
-// of the contract according to the backing database.
+// SetCallCode sets the code of the contract and address of the backing data
+// object
 func (self *Contract) SetCallCode(addr *common.Address, code []byte) {
 	self.Code = code
 	self.CodeAddr = addr