Python: Consistenly use parameter instead of argument in docs

The Python 3 FAQ states that this is the right thing [0]

It sadly doesn't align 100% with PEP8, which calls them for "arguments" [1], but
after discussion with Taus, we decided to go with "parameter" everywhere to be
consistent.

[0] https://docs.python.org/3/faq/programming.html#faq-argument-vs-parameter
[1] https://www.python.org/dev/peps/pep-0008/#function-and-method-arguments

python/ql/src/Functions/NonCls.qhelp

@@ -5,14 +5,14 @@
 
 
 <overview>
-<p> The first argument of a class method, a new method or any metaclass method
-should be called <code>cls</code>. This makes the purpose of the argument clear to other developers.
+<p> The first parameter of a class method, a new method or any metaclass method
+should be called <code>cls</code>. This makes the purpose of the parameter clear to other developers.
 </p>
 
 </overview>
 <recommendation>
 
-<p>Change the name of the first argument to <code>cls</code> as recommended by the style guidelines
+<p>Change the name of the first parameter to <code>cls</code> as recommended by the style guidelines
 in PEP 8.</p>
 
 </recommendation>

python/ql/src/Functions/NonCls.ql

@@ -1,7 +1,7 @@
 /**
  * @name First parameter of a class method is not named 'cls'
- * @description Using an alternative name for the first argument of a class method makes code more
- *              difficult to read; PEP8 states that the first argument to class methods should be 'cls'.
+ * @description Using an alternative name for the first parameter of a class method makes code more
+ *              difficult to read; PEP8 states that the first parameter to class methods should be 'cls'.
  * @kind problem
  * @tags maintainability
  *       readability
@@ -38,10 +38,10 @@ not first_arg_cls(f) and classmethod_decorators_only(f) and
 not f.getName() = "__new__" and
 (
   if exists(f.getArgName(0)) then
-      message = "Class methods or methods of a type deriving from type should have 'cls', rather than '" + 
-            f.getArgName(0) + "', as their first argument."
+      message = "Class methods or methods of a type deriving from type should have 'cls', rather than '" +
+            f.getArgName(0) + "', as their first parameter."
   else
-      message = "Class methods or methods of a type deriving from type should have 'cls' as their first argument."
+      message = "Class methods or methods of a type deriving from type should have 'cls' as their first parameter."
 )
 
 select f, message

python/ql/src/Functions/NonSelf.py

@@ -1,9 +1,9 @@
 class Point:
-    def __init__(val, x, y):  # first argument is mis-named 'val'
+    def __init__(val, x, y):  # first parameter is mis-named 'val'
         val._x = x
         val._y = y
-		
+
 class Point2:
-    def __init__(self, x, y):  # first argument is correctly named 'self'
+    def __init__(self, x, y):  # first parameter is correctly named 'self'
         self._x = x
         self._y = y

python/ql/src/Functions/NonSelf.ql

@@ -1,7 +1,7 @@
 /**
- * @name First argument of a method is not named 'self'
- * @description Using an alternative name for the first argument of an instance method makes
- *              code more difficult to read; PEP8 states that the first argument to instance
+ * @name First parameter of a method is not named 'self'
+ * @description Using an alternative name for the first parameter of an instance method makes
+ *              code more difficult to read; PEP8 states that the first parameter to instance
  *              methods should be 'self'.
  * @kind problem
  * @tags maintainability