Minor fix in using mirror url for residue loading and also adding one more check to see if mirror url should be used.

git-svn-id: https://svn.code.sf.net/p/genoviz/code/trunk@15595 80d5a9c2-7d8c-4c9f-9369-4e03bca4d2bd
Use only one method to check if mirror site should be used

git-svn-id: https://svn.code.sf.net/p/genoviz/code/trunk@15596 80d5a9c2-7d8c-4c9f-9369-4e03bca4d2bd
Merge remote-tracking branch 'upstream'