Rework OSX Readme

- Make more current
- remove cruft
- make readline requirement explicit
- add some historical info
- hopefully make more newbie friendly
Merge pull request #1000 from bagong/patch-1

Rework OSX Readme
A couple of tweaks to the main readme
Copy-editing on the new mac readme
class library: Monitor: take over new fadeTime for releasing old synths
server: added back dumpOSC
thanks to Open Music Kontrollers for spotting what was missing.