I really hate this: complex and twisted logic for a nasty scenario that almost
never happens to short reads - but it may become serious when the reference
genome consists of many contigs.
On toy examples, the code seems to work. Don't know if it really works...
1. Removed bwa.{h,c}. I am not going to finish them anyway.
2. Updated to the latest khash.h, which should be faster.
3. Define 64-bit vector and 128-bit integer/vector in utils.h.
Heng Li