Made static String::hash() capable of incremental hashing.


git-svn-id: http://yate.null.ro/svn/yate/trunk@5859 acf43c95-373e-0410-b603-e72c3f656dc1
Added hashing support for MimeSdpBody.
Speed up MimeSdpBody::addLine() and made it return the added line.


git-svn-id: http://yate.null.ro/svn/yate/trunk@5860 acf43c95-373e-0410-b603-e72c3f656dc1
Increment the SDP session version only if the hash of the body (except version) has changed.
This helps with some SIP endpoints that reject any SDP change.


git-svn-id: http://yate.null.ro/svn/yate/trunk@5861 acf43c95-373e-0410-b603-e72c3f656dc1
Support forcing to generate a SIP reINVITE.


git-svn-id: http://yate.null.ro/svn/yate/trunk@5862 acf43c95-373e-0410-b603-e72c3f656dc1