This aligns the autotools build with the cmake build, which doesn't have
a config.h file. It also removes the ambiguity of config.h and
other/bootstrap_daemon/src/config.h.
* add freezing and unfreezing of peers
* add rejoin packet
* revise handling of temporary invited connections
* rename "peer kill" packet to "peer leave" packet
* test rejoining in conference test
* use custom clock in conference test