README: fixes some md issues + adds limitations

Author: PierreRaybaut

README.md

@@ -1,8 +1,6 @@
-python-qwt
-==========
+# python-qwt
 
-Purpose and Motivation
-----------------------
+## Purpose and Motivation
 
 The ``python-qwt`` project was initiated to solve -at least temporarily-
 the obsolescence issue of `PyQwt` (the Python-Qwt C++ bindings library)
@@ -13,69 +11,60 @@ writing new modules based on NumPy and other libraries.
 The ``python-qwt`` package consists of a single Python package named
 `qwt` and of a few other files (examples, doc, ...).
 
+## Copyrights
 
-Copyrights
-----------
-
-### Main code base ###
-Copyright (c) 2002 Uwe Rathmann, for the original Qwt C++ code
-Copyright (c) 2015 Pierre Raybaut, for the Qwt C++ to Python
+#### Main code base
+  - Copyright © 2002 Uwe Rathmann, for the original Qwt C++ code
+  - Copyright © 2015 Pierre Raybaut, for the Qwt C++ to Python
 translation and optimization
-Copyright (c) 2015 Pierre Raybaut, for the python-qwt specific and
+  - Copyright © 2015 Pierre Raybaut, for the python-qwt specific and
 exclusive Python material
 
-### PyQt, PySide and Python2/Python3 compatibility modules ###
-Copyright (c) 2009-2013 Pierre Raybaut
-Copyright (c) 2013-2015 The Spyder Development Team
+#### PyQt, PySide and Python2/Python3 compatibility modules
+  - Copyright © 2009-2013 Pierre Raybaut
+  - Copyright © 2013-2015 The Spyder Development Team
 
-### Some examples ###
-Copyright (C) 2003-2009 Gerard Vermeulen, for the original PyQwt code
-Copyright (c) 2015 Pierre Raybaut, for the PyQt5/PySide port and
+#### Some examples
+  - Copyright © 2003-2009 Gerard Vermeulen, for the original PyQwt code
+  - Copyright © 2015 Pierre Raybaut, for the PyQt5/PySide port and
 further developments (e.g. ported to python-qwt API)
 
-
-License
--------
+## License
 
 The `qwt` Python package was partly (>95%) translated from Qwt C++
 library: the associated code is distributed under the terms of the LGPL
 license. The rest of the code was either wrote from scratch or strongly
 inspired from MIT licensed third-party software.
 See included LICENSE file for more details about licensing terms.
 
-
-Overview
---------
+## Overview
 
 The `qwt` package is a pure Python implementation of Qwt C++ library with
 the following limitations.
 
-The following `Qwt` classes won't be reimplemented in `qwt` because most
-powerful features already exist in `guiqwt`:
-- QwtPlotZoomer
-- QwtCounter
-- QwtEventPattern
-- QwtPicker
-- QwtPlotPicker
+The following `Qwt` classes won't be reimplemented in `qwt` because more
+powerful features already exist in `guiqwt`: `QwtPlotZoomer`, 
+`QwtCounter`, `QwtEventPattern`, `QwtPicker`, `QwtPlotPicker`.
 
-QwtClipper is not implemented yet (and it will probably be very difficult
-or impossible to implement it in pure Python without performance issues).
-As a consequence, when zooming in a plot curve, the entire curve is still
-painted (in other words, when working with large amount of data, there is
-no performance gain when zooming in).
+Only the following plot items are currently implemented in `qwt` (the 
+only plot items needed by `guiqwt`): `QwtPlotItem` (base class), 
+`QwtPlotItem`, `QwtPlotMarker`, `QwtPlotSeriesItem`, `QwtPlotHistogram`, 
+`QwtPlotCurve` 
 
+The `QwtClipper` class is not implemented yet (and it will probably be 
+very difficult or even impossible to implement it in pure Python without 
+performance issues). As a consequence, when zooming in a plot curve, the 
+entire curve is still painted (in other words, when working with large 
+amount of data, there is no performance gain when zooming in).
 
-Dependencies
-------------
+## Dependencies
 
 ### Requirements ###
 - Python >=2.6 or Python >=3.0
 - PyQt4 >=4.4 or PyQt5 >= 5.5
 - NumPy >= 1.5
 
-
-Installation
-------------
+## Installation
 
 From the source package: