title: Core Plot CPLineStyle compile error on readonly property
body: <p>Trying to build Core Plot and use CPLineStyle I get a compile error from this code...</p>
  
  <pre><code>CPLineStyle *lineStyle = [CPLineStyle lineStyle];
  lineStyle.lineColor = [CPColor blackColor];
  </code></pre>
  
  <p>error: object cannot be set - either readonly property or no setter found</p>
  
  <p>The property is @synthesize'd and while it's declared </p>
  
  <pre><code>@property (nonatomic, readonly, retain) CPColor *lineColor;
  </code></pre>
  
  <p>in the header it is redeclared in a category for the class as</p>
  
  <pre><code>@property (nonatomic, readwrite, retain) CPColor *lineColor;
  </code></pre>
  
  <p>The compiler doesn't seem to know about the redeclaration of the property. What's wrong here?</p>
  
  <p>Gonzalo</p>