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*]...
Correct display of white-space characters in description of `isspace`
Merge pull request #8858 from simonp0420/patch-3

Correct display of white-space characters in description of `isspace`
Document clear_malloc_data
Move clear_malloc_data into Profile and add more documentation
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
Delete redundant export
fix #8865, comprehension evaluated in wrong module

this was because the REPL task was still "in" the old Main
module, and `expand` depends on the current module but doesn't take
a module argument. fortunately there doesn't seem to be any need to
call `expand` explicitly here.
Merge branch 'master' of github.com:JuliaLang/julia
Start at modal prefix searching.
More progress on modal prefix search.
More progress.
Missed cleanup.
Initialize PrefixHistoryPrompt
Minor bugfixing.