1.modify checkpoint,compare checkpoint height with chanActive tip height.
2.if don't have checkpoint block, disconnect block to checkpoint previous height.
3.checkblock function add checkpoint.
Signed-off-by: franklin <flin1866@gmail.com>
modify checkpoints

Signed-off-by: franklin <flin1866@gmail.com>
Merge remote-tracking branch 'remotes/franklin/master' into workspace