modified type SipUrl

-	new subtypes (UriComponents, SipUriComponents, UrnUriComponents, TelUriComponents)

new type RequestUnion

New header fields: SessionId, SIP_ETag, SIP_If_Match

Removal (to be included from/via new import LibSip_MessageBodyTypes)
-	import of LibSip_SDPTypes, LibSip_XMLTypes, LibSip_SimpleMsgSummaryTypes
-	types MessageBody, MIMETypes