[WIP] Do not use prefix importing objects of classes where the prefix is not used

in the export path. These classes are:

• PortalTypeWorkflowChainTemplateItem
• PortalTypeRolesTemplateItem
• PortalTypeAllowedContentTypeTemplateItem
• PortalTypeHiddenContentTypeTemplateItem
• PortalTypePropertySheetTemplateItem
• PortalTypeBaseCategoryTemplateItem

In each class the prefix is used only in preinstall both for current business template and the previously installed ones. The use of prefix in preinstall is twofold:

• To have unique keys in the dictionary of modified objects
• To preserve compatibility with old business templates

@jerome @tc I submit since we already talked about this issue to check mostly on the below:

• This way we use manual prefix only in preinstall. Since it is not fully eliminated though I do not know how much it is worth to apply.
• Do you know why different classes are exported using different folder structures? I mean for example:
  • PortalTypeWorkflowChainTemplateItem objects (workflow_chain_type.xml) are exported directly to the folder.
  • PropertySheetTemplateItem objects are exported in a sub-folder named portal_property_sheets. The intermediate layer is always empty I think, i.e. nothing is exported directly to PropertySheetTemplateItem folder.
• I have no idea how compatibility to business templates installed with previous revision of code can be automatically tested.