context: Don't try to connect to the system instance

In our "cascaded setup", the connection to the system instance happens
via a tunnel in the user instance, so clients should always connect to
the user instance.

Change-Id: Ic5281f2eb1f7c8ae8440e8d065dfc113c72a14cc
system-instance-proxy: New module for automatic mirroring of system instance's sinks

Support for source mirroring should be added too at some point.

Change-Id: I3d41936451572b6341cfb9717e07b355d8449490
tunnel-sink-new: Limit the maximum latency to 200 ms

The default maximum latency is 10 seconds, which is not good,
especially since the tunnel sink doesn't support rewinding. Due to the
lack of rewinding, e.g. volume changes take a long time with large
latencies.

Change-Id: I13753d30a17598ebc9e6a3eda3db4096ff6fcf4e
tunnel-sink-new: Fix requested latency check

This fixes a bug in latency configuration. The wrong type in the cast
caused UINT64_MAX being not treated as special, so the configured
latency was set to UINT64_MAX usecs, which of course is absurdly huge
latency.

Change-Id: Iec239e7970944ed920837580a09bfe76a2ae2bfd
default.pa: Don't load module-udev-detect

In our "cascaded setup" all hardware devices are managed by the system
instance.

Change-Id: I37ca5359d3e4e0fb915895863a0e6bb86528030f