ReadFile() does not seem to update the offset at all.

Closes #1560

59658a8 changed uv_thread_self()
to return uv_thread_t, but uv_thread_t is a thread's HANDLE while
uv_thread_self() returns the current thread's id.
This means that uv_thread_equal() is also broken, as we are
potentially comparing HANDLES to ids.

Changed uv_thread_self() to return the current thread's creation handle.
Fixed small doc issue.

This commit adds x32 support to the gyp build.  Configure with:

    $ ./gyp_uv.py -Dtarget_arch=x32

The existing probes, all two of them, cause a great deal of pain for
people trying to build libuv on Linux because of SystemTap's dtrace(1)
utilitity not understanding the -xnolibs flag.

We could hack around that but it's easier to just remove the probes:
they are largely useless and unused while still needing a lot of
supporting infrastructure.  This commit removes 200 lines of code
and configuration.

Refs #1478.

Changes since version 1.0.0-rc2:

* doc: fix git/svn url for gyp repo in README (Emmanuel Odeke)

* windows: fix fs_read with nbufs > 1 and offset (Unknown W. Brackets)

* win: add missing IP_ADAPTER_UNICAST_ADDRESS_LH definition for MinGW
  (huxingyi)

* doc: mention homebrew in README (Mikhail Mukovnikov)

* doc: add learnuv workshop to README (Thorsten Lorenz)

* doc: fix parameter name in uv_fs_access (Saúl Ibarra Corretgé)

* unix: use cfmakeraw() for setting raw TTY mode (Yuri D'Elia)

* win: fix uv_thread_self() (Alexis Campailla)

* build: add x32 support to gyp build (Ben Noordhuis)

* build: remove dtrace probes (Ben Noordhuis)

* doc: fix link in misc.rst (Manos Nikolaidis)

* mailmap: remove duplicated entries (Saúl Ibarra Corretgé)

* gyp: fix comment regarding version info location (Saúl Ibarra
  Corretgé)

Closes #1572