Fixed issue where setup.py wasn't working when not run from the current directory

setup.py

@@ -2,13 +2,17 @@
 
 # $Id$
 
+import os
 from setuptools import find_packages
 
+_this_dir = os.path.dirname(__file__)
+_long_description = open(os.path.join(_this_dir, 'README.txt')).read().strip()
+
 setup_params = dict(
 	name = "svg.charts",
 	version = "2.0.5",
 	description = "Python SVG Charting Library",
-	long_description = open('README.txt').read().strip(),
+	long_description = _long_description,
 	author = "Jason R. Coombs",
 	author_email = "jaraco@jaraco.com",
 	url = "http://py-svg.sourceforge.net",
@@ -28,7 +32,6 @@ setup_params = dict(
 		"Intended Audience :: Science/Research",
 		"Programming Language :: Python",
 		"License :: OSI Approved :: MIT License",
-		"Topic :: Multimedia :: Graphics :: Presentation",
 	],
 	entry_points = {
 	},