All operations will now yield appropriately, allowing them to be used
freely in concurrent applications. This commit also deprecates the
functions listed below, although they won't raise deprecation
warnings until OTP 21:

zlib:adler32
zlib:crc32
zlib:inflateChunk
zlib:getBufSize
zlib:setBufSize

The behavior of throwing an error when a dictionary is required for
decompression has also been deprecated.

Add functions to 'code' to allow loading of multiple modules
at once.

code:atomic_load(Modules) will load all modules at once, or fail
having loaded none of them. Since we cannot guarantee the atomicity if
there are modules with -on_load functions, the list of modules must
not contain any modules with an -on_load function.

Also, to make it possible to put an application into an inactive state
for as short time as possible, also add code:prepare_loading/1 and
code:finish_loading/1. They are used like this:

  {ok,Prepared} = code:prepare_loading(Modules)
    .
    .
    .
  ok = code:finish_loading(Prepared)

code:ensure_modules_loaded/1 is useful as a pure optimization to
ensure that modules that will be needed soon have indeed been
loaded. It will not reload modules that have already been loaded and
it *will* accept modules that have an on_load function. Therefore, it
does not make sense to give any atomicity guarantees.

I did consider overloading the existing code:ensure_loaded/1
function, but rejected it because the return value is very
different. Having different forms of return values depending
on the types of arguments is confusing.

Since no test suites includede test_server.hrl, there is no need
to have test_server in the include path or code path.

Smoke tests are meant to verify that a build of erlang has been successfull.