Topic can have list of RelatedTopics instead.

Similar fix for RelatedTopics as done in #36 for Bitmaps.
Have a list of related topics.
Removed maxoccurs where not needed
Merge remote-tracking branch 'upstream/master'
Reverted Commit: 8465e23a163eb9628889bba56b58cf1a147ab1cd [8465e23]
VisualizationInfo can have only one Bitmap #36
Correct fix for #36
Changes in Markup.xsd not needed
Merge pull request #44 from rahulsule/master

VisualizationInfo can have only one Bitmap #36