Add hello world example.
Assemblage's assemble.ml remove a useless link_all.
Assemblage API: least surprise rename ?link_all to ?linkall.
Add As_flags.vmthread.
Add threads example.
ocamldep rule: don't include pkg dependencies.

Also tries to keep local deps flags as ordered as possible.
ocamlfind resolver. Hack to compile with -thread.
Add threads-lib example.

Not formally in the test suite, we need to be able to define
bytecode only libraries first.
Merge pull request #99 from dbuenzli/threads-biz

Compiling with threads.