Make the supplementary custom attribute annotations general purpose

[MichalStrehovsky]

We need to make sure all things can be annotated:

• Assemblies
• Nested types
• Methods
• etc.

[marek-safar]

I'd consider using XML for this. The verbosity and the flexibility (e.g. adding comments) of the XML format might be an advantage in this case.

[tlakollo]

The following it's a proposal on how I think the XML would look like:

<Annotations>
  <Assembly Name="Test">
    <Attribute Name="AssemblyAttr" Parameters="SomeParameter"/>
    <Module>
      <Attribute Name="ModuleAttr" Parameters="SomeParameter"/>
    </Module>
    <Namespace Name="System.Collections">
      <Type Name="TypeName">
        <Attribute Name="TypeAttr" Parameters="SomeParameter"/>
        <Field Name="FieldName">
          <Attribute Name="FieldAttr" Parameters="SomeParameter"/>
        </Field>
        <Method Name="MethodName" Signature="">
          <Attribute Name="MethodAttr" Parameters="SomeParameter"/>
          <Parameter></Parameter>
            <Attribute Name="ParameterAttr" Parameters="SomeParameter"/>
          <ReturnParameter>
            <Attribute Name="ReturnParameterAttr" Parameters="SomeParameter"/>
          </ReturnParameter>
        </Method>
      </Type>
      <Type Name="NestedType">
        <Type Name="NestedType2">
          <Attribute Name="AllowMultipleAttr"/>
          <Attribute Name="AllowMultipleAttr" Parameters="SomeParameter"/>
        </Type>
      </Type>
    </Namespace>
  </Assembly>
</Annotations>

In this case the type could be a class, struct, interface or delegate

[marek-safar]

I think the attribute description needs more thoughts. The proposed

        <Attribute Name="TypeAttr" Parameters="SomeParameter"/>

does not cover all cases (e.g. Properties and multiple parameters) and it does not allow to specify the attribute name fully. Something like this might work better

        <Attribute FullName="TypeAttr" AssemblyName="Optional">
			<Arguments>
				<Argument>Value</Argument>
			</Arguments>
			<Fields>
				<Field Name="Name">Value</Field>
			</Fields>
			<Properties>
				<Property Name="Name">Value</Property>
			</Properties>
		</Attribute>

[vitek-karas]

Fixed by #1176.