add Momentum strategy

Author: dongwonmoon

axelrod/strategies/_strategies.py

@@ -193,6 +193,7 @@
 from .memorytwo import AON2, MEM2, DelayedAON1
 from .memorytwo import MemoryTwoPlayer  # pylint: disable=unused-import
 
+from .momentum import Momentum
 from .mutual import Desperate, Hopeless, Willing
 from .negation import Negation
 from .oncebitten import FoolMeOnce, ForgetfulFoolMeOnce, OnceBitten
@@ -402,6 +403,7 @@
     MEM2,
     MathConstantHunter,
     Michaelos,
+    Momentum,
     NTitsForMTats,
     NaiveProber,
     Negation,

docs/index.rst

@@ -53,7 +53,7 @@ Count the number of available players::
 
     >>> import axelrod as axl
     >>> len(axl.strategies)
-    241
+    242
 
 Create matches between two players::
 

docs/reference/strategy_index.rst

@@ -76,6 +76,8 @@ Here are the docstrings of all the strategies in the library.
    :members:
 .. automodule:: axelrod.strategies.memoryone
    :members:
+.. automodule:: axelrod.strategies.momentum
+   :members:
 .. automodule:: axelrod.strategies.meta
    :members:
 .. automodule:: axelrod.strategies.mutual

run_mypy.py

@@ -41,6 +41,7 @@
     "axelrod/strategies/mathematicalconstants.py",
     "axelrod/strategies/memoryone.py",
     "axelrod/strategies/memorytwo.py",
+    "axelrod/strategies/momentum.py",
     "axelrod/strategies/mutual.py",
     "axelrod/strategies/negation.py",
     "axelrod/strategies/oncebitten.py",