Code cleaning in export feature.

git-svn-id: https://svn.code.sf.net/p/genoviz/code/trunk@15753 80d5a9c2-7d8c-4c9f-9369-4e03bca4d2bd
Refactoring and creating headless export class.

git-svn-id: https://svn.code.sf.net/p/genoviz/code/trunk@15754 80d5a9c2-7d8c-4c9f-9369-4e03bca4d2bd
Merge remote-tracking branch 'upstream'