Added custom footer capability. All options for footer are stored in the db. Reworked admin UI to better organize (footer added a lot of options. To-do before release: move options to separate db table to keep from bloating wp_options table; make certain that upon uninstall, we clean up; provide for import/export of settings. Still more isset things to squash.

git-svn-id: https://plugins.svn.wordpress.org/wp-post-to-pdf-enhanced/trunk@860289 b8457f37-d9ea-0310-8a92-e5e31aec5664