SF bug 996392:  math and cmath docs don't specify radians

Major rewrite of the math module docs.  Slapped in "radians" where
appropriate; grouped the functions into reasonable categories; supplied
many more words to address common confusions about some of the subtler
issues.
diff --git a/Misc/NEWS b/Misc/NEWS
index 55f5a14..4b5fae1 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -139,7 +139,7 @@
 Documentation
 -------------
 
-Improved the tutorial on creating types in C.
+- Improved the tutorial on creating types in C.
 
   - point out the importance of reassigning data members before
     assigning thier values
@@ -148,6 +148,7 @@
 
   - mention the labor saving Py_VISIT and Py_CLEAR macros.
 
+- Major rewrite of the math module docs, to address common confusions.
 
 New platforms
 -------------