This commit fixes the display of the recording time in the IDE gui. It
also adds a hook to the pause and resume recording functions.

For the server GUI window, the SimpleController should take the view as
dependant.

This is symmetric to `register`.

Stethoscope calls `serverTree` already.

- a minor API change: the methods called on Volume are adopted to
standard usage: numChans (deprecated) is now numChannels.

- refactoring of the code, use method instead of function for update.

This is a rather large refactoring, but because of its
interdependencies is hard to dissect into pieces.

– move functionality between Server and NetAddr
- simplify Buffer allocation methods
- unify code formatting
- move recording functionality to recorder class
- moves recording defaults to ServerOptions
- makes hack unnecessary for reserved recording buffers
- print more informative messages
- deprecates the `set_` class method (replaced by `all_` already long
ago).

This reverts commit e8879ba.

Same as supercollider#2405, but keeps this branch functional.

The server model checks before boot if it can reach its address. If
this works, it quits the server app first, so that it doesn’t run into
duplicate clientIDs. This allows us to recover better when sclang has
crashed and couldn’t release its server notification id and its shared
memory.