Content core macro

Use content-core instead of main macro for templates using the main_template's master macro. Among fitting better in the standard plone environment and prepares for displaying in a full view (some modifications needed).

Please note, the pull-req is a bit outdated, as it was done on an earlier version of PFG.
Note this: formEpilogue and plone.belowcontentbody would be changed in place .... when using the content-core macro, the belowcontentbody comes later on.
For me, thats something I could live with... Any comments?