accept patch from Роман Шишнев to fix:
1. cpu usage, partclone uses too much cpu. The main problem is too short buffer (fs block size) for almost all io operations. To increase buffer size I had to rewrite most part of main.c.
2. duplicate code, duplicated bugs.

after patch which contains all my changes for partclone, Now the cpu usage is the only crc-checksumming.