Python release 0.5.0 (#693)

* New README file

README.md

@@ -1,10 +1,25 @@
-Installation
-------------
 
-See the `INSTALL.md` document.
+Accelerator Toolbox (AT) is a collection of tools to model storage rings and beam transport lines.
 
-Online documentation
---------------------
+With AT, it is possible to:
+
+- **create and manipulate accelerator lattice elements**,
+- **track particles through the lattice**, selecting the appropriate integrator to represent the physics
+- **compute accelerator parameters and beam properties**, generating new scripts or taking advantage of the existing ones
+
+AT is based on a 6-D modular tracking engine written in C/C++ for efficiency.
+Lattice manipulation and computation of accelerator physics parameters are provided
+by two interfaces:
+
+- a [Matlab interface](https://atcollab.github.io/at/m/index.html), available as a Matlab toolbox,
+- a [python interface](https://atcollab.github.io/at/p/index.html#), available as a python package.
+
+## Installation
+
+- For [Matlab](https://atcollab.github.io/at/m/Installation.html)
+- For [python](https://atcollab.github.io/at/p/howto/Installation.html)
+
+## Online documentation
 
 - Check the [Web site](https://atcollab.github.io/at/)
 - Check the [WIKI](https://github.com/atcollab/at/wiki)