* [DCG_COLLECTION,SC] Various cleanups.
* [DCG_GENERICS,NEW] Added dcg_yn_separator//2.
* [DCG_META,SC] Removed ';'//2.
* [DCG_META,EXT] Added dcg_call//6.
* [DCG_META,NEW] Added scg_sequence//2.
* [META_EXT,DOC] Added example for default/2.
* [XML_ELEMENT,SC] Cleanup of meta-DCG code.