Added wxTEXT_ATTR_AVOID_PAGE_BREAK_AFTER, wxTEXT_ATTR_AVOID_PAGE_BREAK_BEFORE attributes


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75141 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775