Activate the options that were previously set with calls to option
setters.
This allows to defer activiation of the options until all
options have been set. This is required for components which have
related options that remain ambigous until all are set.
For example, the FileAppender has the {@link
org.apache.log4j.FileAppender#setFile File} and {@link
org.apache.log4j.FileAppender#setAppend Append} options both of
which are ambigous until the other is also set.
