Astviewer

* Source code is shown in a dock-widget.

* Fixed setup.py to work when PyQt is not intalled.

* Works with Python 3.

* Works with PyQt5.

* Persistent state (e.g. window size/pos) across sessions.

* Assumes Python files are UTF-8 encoded instead of ASCII.

* Clicking the text will select the corresponding node in the tree.

* Highlighting works recursively. Still not perfect, see Issue 1:
https://github.com/titusjan/astviewer/issues/1

* Added setup.py installer

* Made separate (pyasterviewer) command line application
and (asterviewer.py) module.

* The AstViewer class constructor accepts a source_code
parameter so source can be compared from a string.

* The AstViewer class constructor accepts a mode parameter

* Bug fix: highlighting of the last element now works.