[core/theme] Add iconset support

Allow themes to specify iconsets. To do so, add a new util library
"util.algorithm", which currently contains support for deep merging of
dicts.

tests/util/test_algorithm.py

@@ -0,0 +1,40 @@
+import unittest
+
+from util.algorithm import *
+
+class algorithm(unittest.TestCase):
+    def setUp(self):
+        self.someData = {'a': 100, 'b': 200, 'c': [1,2,3]}
+        self.differentData = {'x': 20, 'y': 'bla', 'z': ['a','b']}
+        self.moreData = {'n': 100}
+        self.overlapData = {'a': 200, 'c': [1,2,4]}
+
+    def test_merge_with_empty(self):
+        self.assertEqual(self.someData, merge(self.someData, {}))
+        self.assertEqual(None, merge(self.someData, None))
+
+    def test_merge_no_overwrite(self):
+        result = merge(self.someData, self.differentData)
+        for k in self.someData:
+            self.assertEqual(result[k], self.someData[k])
+        for k in self.differentData:
+            self.assertEqual(result[k], self.differentData[k])
+
+    def test_merge_multiple(self):
+        result = merge(self.someData, self.differentData, self.moreData)
+        for k in self.someData:
+            self.assertEqual(result[k], self.someData[k])
+        for k in self.differentData:
+            self.assertEqual(result[k], self.differentData[k])
+        for k in self.moreData:
+            self.assertEqual(result[k], self.moreData[k])
+
+    def merge_overlap(self):
+        result = merge(self.someData, self.overlapData)
+        for k in self.someData:
+            if not k in self.overlapData:
+                self.assertEqual(result[k], self.someData[k])
+        for k in self.overlapData:
+            self.assertEqual(result[k], self.overlapData[k])
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4