Enable macros within a macro

[ChristophEwertowski]

In our morph file we have multiple blocks of macros, for example:

<call-macro name="setSubjectContributionBnode" field="100"/>
<call-macro name="setRoleForContributionBnode" field="100"/>
<call-macro name="setTypeContributionForContributionBnode" field="100"/>
<call-macro name="setAgentForContributionBnode" field="100"/>
<call-macro name="setBackSubjectContributionBnode" field="100"/>

All it does is adding role, type and agent of a contribution. Since every fourth field from 100 to 296 has to have these elements it would be nice to be able to put them into one "super-macro".