feat: add python3 benchmark runner and fix python3 compatibility in benchmark scripts

Add python3 as a new language entry in the benchmark runner configuration, enabling automated performance testing with Python 3. Update multiple benchmark scripts (binary_trees.py, delta_blue.py, fib.py, for.py, method_call.py) to be compatible with Python 3 by adding `from __future__ import print_function`, replacing `xrange` with a `range` polyfill, converting print statements to function calls, and replacing integer division with floor division. Remove the custom `OrderedCollection` class in delta_blue.py in favor of standard Python lists.

benchmark/for.py

@@ -1,8 +1,16 @@
+from __future__ import print_function
+
 import time
 
+# Map "range" to an efficient range in both Python 2 and 3.
+try:
+    range = xrange
+except NameError:
+    pass
+
 start = time.clock()
 list = []
-for i in xrange(0, 1000000):
+for i in range(0, 1000000):
   list.append(i)
 
 sum = 0