Cleanup session and state handling

...janne/libquassel/protocol/syncables/common/CertManager.kt

...ustjanne/libquassel/protocol/syncables/common/CoreInfo.kt

...stjanne/libquassel/protocol/syncables/common/DccConfig.kt

...quassel/protocol/syncables/common/HighlightRuleManager.kt

...ustjanne/libquassel/protocol/syncables/common/Identity.kt

...libquassel/protocol/syncables/common/IgnoreListManager.kt

...tjanne/libquassel/protocol/syncables/common/IrcChannel.kt

...nne/libquassel/protocol/syncables/common/IrcListHelper.kt

...justjanne/libquassel/protocol/syncables/common/IrcUser.kt

...justjanne/libquassel/protocol/syncables/common/Network.kt

...nne/libquassel/protocol/syncables/common/NetworkConfig.kt

...tjanne/libquassel/protocol/syncables/common/RpcHandler.kt

...stjanne/libquassel/protocol/syncables/AliasManagerTest.kt

...de/justjanne/libquassel/protocol/syncables/NetworkTest.kt

...assel/protocol/testutil/mocks/EmptyProxyMessageHandler.kt

...tjanne/libquassel/protocol/testutil/mocks/EmptySession.kt

...anne/libquassel/protocol/testutil/mocks/EmptySyncProxy.kt