v0.58.1

The first release in a long time, ready for testing and improvement... The big difference between the 0.57 and 0.58 versions is a much leaner internal protocol (ie. uses less network bandwidth, hopefully less exposed to network collisions etc as number of ensemble members increases) - with no change to the "external" OSC protocol used for communication with other local computer music software. (As usual, binaries are provided here for OSX and Windows [Windows requires separate GNU OpenStep installation] - Linux users should clone the repository and build from source.)