Add Python 3 modules, and more Python 2 modules.

Also, sort names alphabetically and add module docstrings.

python3/cmath.py

@@ -0,0 +1,48 @@
+"""Stub file for the 'cmath' module."""
+# This is an autogenerated file. It serves as a starting point
+# for a more percise manual annotation of this module.
+# Feel free to edit the source below, but remove this header when you do.
+
+def acos(*args, **kwargs) -> complex: pass
+
+def acosh(*args, **kwargs) -> complex: pass
+
+def asin(*args, **kwargs) -> complex: pass
+
+def asinh(*args, **kwargs) -> complex: pass
+
+def atan(*args, **kwargs) -> complex: pass
+
+def atanh(*args, **kwargs) -> complex: pass
+
+def cos(*args, **kwargs) -> complex: pass
+
+def cosh(*args, **kwargs) -> complex: pass
+
+def exp(*args, **kwargs) -> complex: pass
+
+def isfinite(a: complex) -> bool: pass
+
+def isinf(a: complex) -> bool: pass
+
+def isnan(a: complex) -> bool: pass
+
+def log(a: complex, *args, **kwargs) -> complex: pass
+
+def log10(*args, **kwargs) -> complex: pass
+
+def phase(a: complex) -> float: pass
+
+def polar(a: complex) -> tuple: pass
+
+def rect(a: float, b: float) -> complex: pass
+
+def sin(*args, **kwargs) -> complex: pass
+
+def sinh(*args, **kwargs) -> complex: pass
+
+def sqrt(*args, **kwargs) -> complex: pass
+
+def tan(*args, **kwargs) -> complex: pass
+
+def tanh(*args, **kwargs) -> complex: pass