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/binary_trees.py

@@ -4,16 +4,24 @@
 # contributed by Antoine Pitrou
 # modified by Dominique Wahli
 # modified by Heinrich Acker
+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
+
 def make_tree(item, depth):
     if not depth: return item, None, None
     item2 = item + item
     depth -= 1
     return item, make_tree(item2 - 1, depth), make_tree(item2, depth)
 
-def check_tree((item, left, right)):
+def check_tree(node):
+    item, left, right = node
     if not left: return item
     return item + check_tree(left) - check_tree(right)
 
@@ -22,19 +30,19 @@ max_depth = 12
 stretch_depth = max_depth + 1
 
 start = time.clock()
-print "stretch tree of depth %d check:" % stretch_depth, check_tree(make_tree(0, stretch_depth))
+print("stretch tree of depth %d check:" % stretch_depth, check_tree(make_tree(0, stretch_depth)))
 
 long_lived_tree = make_tree(0, max_depth)
 
-iterations = 2**max_depth
-for depth in xrange(min_depth, stretch_depth, 2):
+iterations = 2 ** max_depth
+for depth in range(min_depth, stretch_depth, 2):
 
     check = 0
-    for i in xrange(1, iterations + 1):
+    for i in range(1, iterations + 1):
         check += check_tree(make_tree(i, depth)) + check_tree(make_tree(-i, depth))
 
-    print "%d trees of depth %d check:" % (iterations * 2, depth), check
-    iterations /= 4
+    print("%d trees of depth %d check:" % (iterations * 2, depth), check)
+    iterations //= 4
 
-print "long lived tree of depth %d check:" % max_depth, check_tree(long_lived_tree)
+print("long lived tree of depth %d check:" % max_depth, check_tree(long_lived_tree))
 print("elapsed: " + str(time.clock() - start))