Added Lots of Documentation

Added some nice to haves
Improved and Unified General Code Layout

MathKit/MPExpression.h

@@ -10,6 +10,9 @@
 
 /*!
  @header
+ This file contains the <code>MPExpression</code> class and the
+ <code>MPExpressionElement</code> protocol.
+
  The <code>MPExpression</code> class is used to represent a mathematical
  expression. It is used in the storage layer of the MathKit Expression System. An
  instance of the <code>MPExpression</code> class stores all contents related to
@@ -108,6 +111,58 @@
  */
 
 
+/*!
+    @const      MPIllegalElementException
+    @abstract   Name for an exception that is raised if an invalid element is
+                added to an expression.
+ 
+    @discussion This exception may be raised during initialization of an
+                expression or when the expression is mutated. This exception
+                contains the invalid element in its <code>userInfo</code>
+                dictionary. You can query it using the
+                <code>MPIllegalElementExceptionElementKey</code> key.
+ */
+FOUNDATION_EXPORT NSString *const MPIllegalElementException;
+
+
+/*!
+    @const      MPIllegalElementExceptionElementKey
+    @abstract   Predefined key for an invalid element that caused a
+                <code>MPIllegalElementException</code> to be raised.
+ 
+    @discussion The invalid element can be of any type. Numbers and structs are
+                wrapped in an <code>NSNumber</code> or <code>NSValue</code>
+                instance respectively.
+ */
+FOUNDATION_EXPORT NSString *const MPIllegalElementExceptionElementKey;
+
+
+/*!
+    @typedef    MPReferenceFrame
+    @abstract   A reference frame specifies the way an <i>item</i> is to be
+                interpreted.
+ 
+    @constant   MPElementReferenceFrame
+                Specifies that items should be interpreted as elements.
+ 
+    @constant   MPSymbolReferenceFrame
+                Specifies that items should be interpreted as symbols.
+ 
+    @constant   MPTokenReferenceFrame
+                Specifies that items should be interpreted as tokens.
+  */
+typedef enum {
+    MPElementReferenceFrame,
+    MPSymbolReferenceFrame,
+    MPTokenReferenceFrame
+} MPReferenceFrame;
+
+
+
+@class MPExpression, MPFunction, MPRangePath, MPParsedExpression;
+@protocol MPExpressionElement, MPToken;
+
+
 /*!
     @protocol   MPExpressionElement
     @abstract   This protocol defines the functionality an element in an
@@ -161,58 +216,6 @@
 
 
 
-/*!
-    @const      MPIllegalElementException
-    @abstract   Name for an exception that is raised if an invalid element is
-                added to an expression.
- 
-    @discussion This exception may be raised during initialization of an
-                expression or when the expression is mutated. This exception
-                contains the invalid element in its <code>userInfo</code>
-                dictionary. You can query it using the
-                <code>MPIllegalElementExceptionElementKey</code> key.
- */
-FOUNDATION_EXPORT NSString *const MPIllegalElementException;
-
-
-/*!
-    @const      MPIllegalElementExceptionElementKey
-    @abstract   Predefined key for an invalid element that caused a
-                <code>MPIllegalElementException</code> to be raised.
- 
-    @discussion The invalid element can be of any type. Numbers and structs are
-                wrapped in an <code>NSNumber</code> or <code>NSValue</code>
-                instance respectively.
- */
-FOUNDATION_EXPORT NSString *const MPIllegalElementExceptionElementKey;
-
-
-/*!
-    @typedef    MPReferenceFrame
-    @abstract   A reference frame specifies the way an <i>item</i> is to be
-                interpreted.
- 
-    @constant   MPElementReferenceFrame
-                Specifies that items should be interpreted as elements.
- 
-    @constant   MPSymbolReferenceFrame
-                Specifies that items should be interpreted as symbols.
- 
-    @constant   MPTokenReferenceFrame
-                Specifies that items should be interpreted as tokens.
-  */
-typedef enum {
-    MPElementReferenceFrame,
-    MPSymbolReferenceFrame,
-    MPTokenReferenceFrame
-} MPReferenceFrame;
-
-
-
-@class MPExpression, MPFunction, MPRangePath, MPParsedExpression;
-@protocol MPExpressionElement, MPToken;
-
-
 /*!
     @class      MPExpression
     @abstract   A <code>MPExpression</code> instance represents a mathematical