add README.md

README.md

+pyHealpix - minimalistic Python interface for Healpix C++
+=========================================================
+
+Summary
+-------
+
+### Description
+
+This library tries to provide Python bindings for the most important
+functionality in Healpix C++. The design goals are
+- similarity to the C++ interface (while respecting some Python peculiarities)
+- simplicity (no optional function parameters)
+- low function calling overhead
+
+The package is implemented purely in C++, making use of the pybind11 package
+(https://github.com/pybind/pybind11). It can be compiled for both Python 2 and
+3.
+
+
+Installation
+------------
+
+### Requirements
+
+- no external dependencies, all required code is contained in the package
+- for building, a modern C++ compiler is required (successfully tested with
+  g++ 5.4 clang 4.0 and Intel icpc 17.0)
+- for building from the Git repository, GNU autotools are required
+
+### System-wide installation
+
+-   Install dependencies for building:
+
+        sudo apt-get install g++ autoconf git
+
+-   Install pyHealpix:
+
+        git clone https://gitlab.mpcdf.mpg.de/ift/pyHealpix.git
+        cd pyHealpix
+        autoreconf -i && ./configure && make -j4 && sudo make install
+        cd ..
+
+### Local installation for a single user
+
+-   Install dependencies for building:
+
+        sudo apt-get install g++ autoconf git
+
+-   Install pyHealpix:
+
+        git clone https://gitlab.mpcdf.mpg.de/ift/pyHealpix.git
+        cd pyHealpix
+        autoreconf -i && ./configure --prefix=$HOME/.local && make -j4 && make install
+        cd ..
+
+### Installation on OS X
+
+-   Install pyHealpix:
+
+        git clone https://gitlab.mpcdf.mpg.de/ift/pyHealpix.git
+        cd pyHealpix
+        autoreconf -i && ./configure --prefix=`python-config --prefix` && make -j4 && sudo make install
+        cd ..