Check span direction.

git-svn-id: https://svn.code.sf.net/p/genoviz/code/trunk@15157 80d5a9c2-7d8c-4c9f-9369-4e03bca4d2bd
Compare with original coordinate box.

git-svn-id: https://svn.code.sf.net/p/genoviz/code/trunk@15158 80d5a9c2-7d8c-4c9f-9369-4e03bca4d2bd
Add method to get average quality score.

git-svn-id: https://svn.code.sf.net/p/genoviz/code/trunk@15159 80d5a9c2-7d8c-4c9f-9369-4e03bca4d2bd
Merge remote-tracking branch 'upstream'