Add preserve-script-closures to config for apps that need it with new event-handler fix

This is not an exclusive list.  We need to continue testing, starting with test/UTF8
Remove erroneous set of "self" to UTF8JsonLoader in its constructor

The global "self" is always assumed to refer to the driver.
Fix bug in utf8 test app
Add config parameter to preserve closures for write-together and xmas-tree apps