Add a simple new (object based) method for creating rk.header()-calls from JS code.
This should be more readable than makeHeaderCode(), particularly when combined with i18n()-calls.
It also makes it easy to define parts of the header in other places of the JS code (such as in the calculate() function).


git-svn-id: https://svn.code.sf.net/p/rkward/code@5004 7936002b-cd1d-0410-9ce3-d7ebf93b5162