Bump up version to v1.7.5 for release,
Include JavaScript only when needed,
Use `restore_current_blog()` instead of `switch_to_blog()`,
Remove PHP 4.0 compatibility code,
Allow other plugins to use saving screen options

git-svn-id: https://plugins.svn.wordpress.org/email-log/trunk@995878 b8457f37-d9ea-0310-8a92-e5e31aec5664