Organize modules

  - all modules have 'type t'
  - all modules specific call backs are called 'cb', multiple callbacks are labeled with a
    more specific postfix (cb_write, et cetera).
  - Only two modules are in a recursive definition, this may be expanded later

Issues
  - some types are not used; it looks like they need functions to turn a set of flags to a
    packed integer, these are preserved but labeled with "UNUSED".
  - the examples/ are not updated in this changeset
Update examples

  - for readability
  - for the new module structure of Uv
  - add build rules for examples
  - add structure for tests/ and build rule

Caveat
  - compilation does not work; types are incorrect (errno <-> int conversion)
wrong readme for installation
update compilation

  - fixed name conflict of object files in compilation
  - removed read2; does not exist in latest libuv
  - added back camluv_threadpool required for linking
  - removed unused import in camluv (now camluv_err).
Merge pull request #10 from nrlucaroni/master

Update compilation; Modernize module layout;