A special topic MUST be part of a ConvNode, because these are inherently meaningful only in context. A special topic is active only when its conversation node is active.
Special topics are automatically Suggested Topics as well as Topic Entries. Because special topics use their own custom grammar, it's unreasonable to expect a player to guess at the custom grammar, so we should always provide a topic inventory suggestion for every special topic.
Alternatively, an instance can specifically define its own custom regular expression pattern instead of using the keyword list; the regular expression allows the instance to include punctuation in the syntax, or apply more restrictive criteria than simply matching the keywords.
This routine adds the topic's keywords to the global dictionary, under the 'special' token type. Since a special topic's keywords are accepted when the special topic is active, it would be wrong for the parser to claim that the words are unknown when the special topic isn't active. By adding the keywords to the dictionary, we let the parser know that they're valid words, so that it won't claim that they're unknown.