GEP 18: * read in template data
        * manage template via SrcTemplate
        * obtain author/pubinfo from attributes via template


git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/branches/geps/gep-018-evidence-style@22469 4ae1f11a-8b86-4847-b8af-ab372f36d1fd