Added Python 3 support.

More or less, the only changes that were required were to do with
unicode vs ascii strings, so where needed, I have added encodings and b
prefixes on strings. Fixes #1.

Author: matthewelse

Model3D.py

@@ -15,6 +15,7 @@ def __init__(self, x, y, z):
 		self.z = float(z)
 
 		key_string = '(%f, %f, %f)' % (self.x, self.y, self.z)
+		key_string = key_string.encode('utf-8')
 		self.hash = md5(key_string).hexdigest()
 
 	def __add__(self, other):
@@ -407,20 +408,20 @@ def __init__(self, f=None):
 		contents = f.read()
 		f.close()
 
-		if contents.find("vertex", 80) == -1:
+		if contents.find(b"vertex", 80) == -1:
 			# File is a binary STL file.
 			self.process_bin(contents)
 		else:
 			self.process_text(contents)
 
 	def process_bin(self, contents=None):
-		self.name, num_facets_1 = unpack("=80sI", contents[:84])
+		self.name, num_facets_1 = unpack(b"=80sI", contents[:84])
 
-		self.name = self.name.replace("solid", "")
-		self.name = self.name.strip('\x00 \t\n\r')
+		self.name = self.name.replace(b"solid", b"")
+		self.name = self.name.strip(b'\x00 \t\n\r')
 
 		if len(self.name) == 0:
-			self.name = "Unkown"
+			self.name = b"Unkown"
 
 		contents = contents[84:]
 		facetsz = len(contents)
@@ -435,7 +436,7 @@ def process_bin(self, contents=None):
 
 		for i in items:
 			nx, ny, nz, f1x, f1y, f1z, f2x, f2y, f2z, f3x, f3y, f3z = \
-				unpack("=ffffffffffffxx", i)
+				unpack(b"=ffffffffffffxx", i)
 			v1 = Vector3(f1x, f1y, f1z)
 			v2 = Vector3(f2x, f2y, f2z)
 			v3 = Vector3(f3x, f3y, f3z)

pySlice.py

@@ -68,9 +68,9 @@ def slice_file(f=None, resolution=0.1):
 
 	interval = scale * resolution
 	stats = model.stats()
-	print stats
+	print(stats)
 
-	for targetz in xrange(0, int(stats['extents']['z']['upper']), int(interval)):
+	for targetz in range(0, int(stats['extents']['z']['upper']), int(interval)):
 		dwg = Drawing('outputs/svg/'+str(targetz)+'.svg', profile='tiny')
 		pairs = model.slice_at_z(targetz)
 		for pair in pairs: