r364: bug in mem pairing (no effect with -A=1)

Forgot to adjust for matching score. This bug has no effect when -A takes the
default value.
r365: bugfix - wrong alignment (right mapping)

The bug only happens when there is a 1bp del and 1bp ins which are close to the
end and there are no other substitutions or indels. In this case, bwa mem gave
a wrong band width.
Release BWA-0.7.3-r366
Release bwa-0.7.3a-r367

In 0.7.3, the wrong CIGAR bug was only fixed in one scenario, but not fixed
in another corner case.
Merge branch 'master' into master_fixes