new option debug_files: port setFileDebugMode() to the option() api

setFileDebugMode() is now deprecated
added event system; subscript using ::on($name, $handler); broadcast using ::trigger($name[, $args,...])
new option gzip: port noGzip() to option('gzip'); new event set_option

set_option: triggeren when setting an option
new option dump_variables: port dumpVariablesOnExit() to option('dump_variables')
new option dump_variables: port dumpVariablesOnExit() to option('dump_variables')