title: PostSharp OnMethodBoundaryAspect
body: <p>I'm working on an aspect with postsharp 1.5 and OnMethodBoundaryAspect. 
  I want my aspect have the following behavior by default:</p>
  
  <p>1-If the attribute is used at class level the aspect is applied only on <strong>PUBLIC</strong> methods.</p>
  
  <p>2-The user of the aspect can put the aspect in a private or protected method.</p>
  
  <p>If I use this
  [MulticastAttributeUsage(
  MulticastTargets.Method, TargetMemberAttributes = MulticastAttributes.Public)]
  the point 1 works, but the case 2 doesn't even build becaue is incompatible.</p>
  
  <p>Then I tried to use:
  AttributeTargetTypeAttributes = MulticastAttributes.Public;
  in the constructor of the aspect, but doesn't work.</p>
  
  <p>Thank you very much in advance.</p>