Integrate changes from upstream/master into csharp-experimental

C# addressbook update

Update addressbook.proto and examples code to proto3

Let GOOGLE_COMPILE_ASSERT use static_assert if available.

Added Ruby to conformance tests.

First part of JSON formatting for well-known types.

First part of JSON formatting for well-known types. I think we need a reflection API rethink before doing the rest.

Change-Id: If7b1cc0f03f609a7f43ddafc8509b44207c60910

Change-Id: Id008ebac5159f773e1bde8b85acb2626cbd16de8

Addming missing includes in stubs headers.

This is to prepare removing those additional headers in common.h

Change-Id: I707d6d8eaf193eb28195a827c7fec738b968ab3e

The motivation is that gcc 4.8+ and clang trunk warn on unused local
typedefs, which COMPILE_ASSERT adds. After this change, the warning
will be happy at least in C++11 builds. static_assert also produces a
slighly nicer diagnostic than the typedef method.

https://github.com/google/re2/commit/eb93e8bc43ac8d05322fb3e9fc885898ad924f8a
did the same change in re2.

Split up common.h headers

ignore UTF-8 BOM

Fix typo in buildall.sh

Change-Id: I75459b8b6562c3ac58fa4b1e4513accdda43ad64

Change-Id: I5f6cbc2430200e3751ad754cc7ae604338db6f91

Change-Id: Ifbc415755266ba3d0ffa5661fcd7c7d2e3b32a22

First pass at the big rename from ProtocolBuffers to Google.Protobuf.

We'll see what I've missed when CI fails...

C# wrapper types

Export c# naming routines publicly

Change-Id: I223783111d743aa5193bf70fa1b9b54c7b4389c3

Fix make distcheck

Run C# tests on Appveyor

This involved fixing a few important bugs in the
Ruby implementation -- mostly cases of mixing
upb field types and descriptor types (upb field
types do not distinguish between int/sint/fixed/sfixed
like descriptor types do).

Also added protobuf-specific exceptions so parse
errors can be caught specifically.

Change-Id: Ib49d3db976900b2c6f3455c8b88af52cfb86e036