Support host count in machinefile

- Support the syntax `[user@]host[:port][*count] [bind_addr]` in the
  machinefile.
- Initial code just re-writes the list fed to addprocs() by repeating the host
  as specified, so there is no user-visible change.
Move the host count to the beginning: [count*]...
Merge branch 'machinefile_count' of git://github.com/wavexx/julia into wavexx-machinefile_count

Conflicts:
	base/client.jl
	doc/manual/getting-started.rst
Merge pull request #8863 from amitmurthy/wavexx-machinefile_count

Wavexx machinefile count
Channel and RemoteChannel