Adding method to refresh individual tiers for future use.

git-svn-id: https://svn.code.sf.net/p/genoviz/code/trunk@15315 80d5a9c2-7d8c-4c9f-9369-4e03bca4d2bd
Fixing operator.

git-svn-id: https://svn.code.sf.net/p/genoviz/code/trunk@15316 80d5a9c2-7d8c-4c9f-9369-4e03bca4d2bd
Fixing getting wrong starting point.

git-svn-id: https://svn.code.sf.net/p/genoviz/code/trunk@15317 80d5a9c2-7d8c-4c9f-9369-4e03bca4d2bd
Do not return a span when where is no pair.

git-svn-id: https://svn.code.sf.net/p/genoviz/code/trunk@15318 80d5a9c2-7d8c-4c9f-9369-4e03bca4d2bd
Merge remote-tracking branch 'upstream'