Putting the test code in the same package makes it easier for forks
since they don't have to change the import paths as much and it also
gets rid of the need for internal_test.go to bridge.
While here, remove the reorganization test since it is much better
handled by the full block tests and is no longer needed and do some
light cleanup on a few other tests.
The full block tests had to remain in the separate test package since it
is a circular dependency otherwise. This did require duplicating some
of the chain setup code, but given the other benefits this is
acceptable.
This commit adds a new function to the blockchain package named
IsCoinBaseTx which performs the same function as IsCoinBase except it
takes raw wire transactions as opposed to the higher level util
transactions.
While here, it also adds a file for benchmarks along with a couple of
benchmarks for the IsCoinBase and IsCoinBaseTx functions.
Finally, the function was very slightly optimized:
BenchmarkIsCoinBaseOld 100000000 10.7 ns/op 0 B/op 0 allocs/op
BenchmarkIsCoinBaseNew 200000000 6.05 ns/op 0 B/op 0 allocs/op
