Add Qt wrapper gist to README as a third party contribution 

This will allow hosting as Github Pages.

* Copied Tutorial from Google Code wiki.

* Initial Home page

* Copied How To Parse A Document from Google Code wiki

* Updated How To Parse A Document (markdown)

* Updated How To Parse A Document (markdown)

* Updated How To Parse A Document (Old API) (markdown)

* Copied How To Emit YAML from Google Code wiki

* Copied Breaking Changes from Google Code wiki

* Copied Strings from Google Code wiki

* Updated Strings (markdown)

* Updated Home (markdown)

* Fix typo.

* Updated Breaking Changes (markdown)

* Updated How To Parse A Document (Old API) (markdown)

* Updated Breaking Changes (markdown)

* Move wiki content to docs/

* Improve markdown and add colored code syntax

Co-authored-by: Jesse Beder <jbeder+github@gmail.com>

Fix stack overflow in HandleNode by explicitly limiting the depth of recursion.

This fixes the linux/gcc error building Google Test with gcc 4.7:

https://travis-ci.org/github/jbeder/yaml-cpp/jobs/668233706

Add check that a move assigned Node gets the same representation as the
moved-from Node had before the move.

It's clearly related to an existing node, so it can have a mark and give
an error location.

This commit updates the version of Google Test from 1.8 to 1.10.

The explicitly defaulted or implemented move constructors and assignment
operators are made "noexcept".

Bugfix:
* src/stream.cpp Stream::Stream() char_traits::int_type intro[4] is
  now aggregate-initialized (to zero) to avoid UB.

Minor changes:
* Using std::isinf() and std::signbit() instead of comparing for
  equality with infinity.
* src/streamcharsource.h: Added #include "stream.h".
* src/stream.h: Forward declaring "class StreamCharSource".
* Some implicit casting changed into static_cast's.

Signed-off-by: Ted Lyngmo <ted@lyncon.se>

This is in preparation for other patches that will make use of the
macro. The patch also removes #undef:ing the macro after its been
used to not make the header inclusion order critical. Otherwise,
the new header would always have to be the last of the yaml-cpp
headers to be included.

E.g. `!2`.

Change the namespace from yaml::yaml to yaml-cpp::yaml-cpp.

Also add a test for a parser with no data

This happens whenever in a macro you use some "if" block, and don't use curly braces {},
as the macro is expanded on a single line, not on several lines. So just add the missing
curly braces to please gcc.

In file included from /remote/users/mlamesch/CloneFromPlatinum/yamlcpp/osp/Yamlcpp/18-0-0-5/include/yaml-cpp/yaml.h:18,
                 from src/TestYaml.cpp:2:
/remote/users/mlamesch/CloneFromPlatinum/yamlcpp/osp/Yamlcpp/18-0-0-5/include/yaml-cpp/node/convert.h: In static member function static bool YAML::convert<int>::decode(const YAML::Node&, int&):
/remote/users/mlamesch/CloneFromPlatinum/yamlcpp/osp/Yamlcpp/18-0-0-5/include/yaml-cpp/node/convert.h:139:1: error: this if clause does not guard... [-Werror=misleading-indentation]
 YAML_DEFINE_CONVERT_STREAMABLE_SIGNED(int);
 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* Showing test output only on failure

* Test commit to see the failed test

* Now making sure that the tests pass with no output

🐛 Fixes #748 (#770)

Also run clang-format on these files as requested

Add empty list of sources to add_library and add_executable.

The generator expressions here are actually unnecessary, now that I think about it.

This should fix #745

Example of how someone might consume yaml-cpp with bazel:

cc_binary(
    name = "example",
    srcs = ["example.cc"],
    deps = ["@com_github_jbeder_yaml_cpp//:yaml-cpp"],
)