large drive-gap fix

• A 6-year-old bug, seen primarily by Whipper users, concerning
  adjusting of CD-drives that have large sample offsets, or negative
  offsets has been fixed. Fix is from and thanks are due to
  buddyabaddon. #14 and #38
• Code has moved from savannah.gnu.org to github. CircleCI
  testing is now incorporated into builds.
• Add test on LSN on span check errors, and give a better
  message when there is a problem. #39
• Require libcdio at least 2.0.0
• Remove dead code after exit. #32
• Fix manpage for Japanese. #27
• Add notes for using gmake for building on FreeBSD.

release-10.2+2.0.1

• cdda toc routines now included (fixes #21)
• "make distcheck" broken in 2.0.0 works properly again
• Remove some gcc/clang warnings