Medium: cib: Overhaul the processing of synchronous replies

• Simplify the logic to be more obvious
• Default call_timeout to the global default
• Timeouts are not strict, they refer olny to a period of inactivity. Therefor the actual delay may be slightly higher if other/older replies are received that don't match the active request

Mercurial revision: 99cf0eb8248488bded2a08e73ec300bb94d878e7