Added a readme file

README.rst

+Simple C++ Logger
+#################
+
+
+Overview
+========
+
+This project provides a simple C++ logger class and API. It supports different logging levels and colorized logging
+output. Logging messages that do not conform to the desired display logging level are filtered in the preprocessor
+stage and do not affect the program runtime. Therefore, you can add as many logging messages as you want without
+affecting cpu or memory usage of the production version of your software.
+
+Currently, Linux and macOS are supported. It is not tested on Windows yet.
+
+
+Usage
+=====
+
+Just add ``logger.cpp`` and ``logger.hpp`` to your project files; they have no dependencies to other libraries. Then
+you can use the global default logger by calling:
+
+.. code-block:: cpp
+
+   logger(DEBUG, << "my logging output of variable x" << x << std::endl);
+
+You can output every variable that can be shifted ``<<`` into a ``std::ostream`` object like ``std::cout`` or
+``std::cerr``.
+
+Currently, 5 levels of logging output are supported. The levels can be enabled or disabled step-by-step to increase or
+decrease the verbosity of the program:
+
+-   ``DEBUG``
+-   ``INFO``
+-   ``WARNING``
+-   ``ERROR``
+-   ``CRITICAL``
+
+Each logging level is displayed in a different color.
+
+The displayed logging levels can be controlled by a ``DEFAULT_LOG_LEVEL`` macro. If it is not set it defaults to
+``DEBUG`` in a debug environment (``NDEBUG`` macro not set). If ``NDEBUG`` is set, the default logging level is
+``WARNING``. The logger can be disabled completely by setting an ``NLOG`` macro. The chosen log level automatically
+includes log levels that are less verbose. For example, if ``WARNING`` is set, ``ERROR`` and ``CRITICAL`` logging
+messages are also printed to screen.
+
+
+Example
+=======
+
+For a small demonstration, you can compile and execute the test program included in the ``src/`` directory by
+entering:
+
+.. code-block:: bash
+
+    make
+    ./test
+
+
+You should get the following output:
+
+.. image:: http://iffwww/pub/media/simple_cpp_logger.gif