converting to new mechanism for default rendition

In TEI P5 2.8.0 and earlier, to specify a default rendition you would
use something like

 | <tagsDecl>
 |   <rendition xml:id="rend.head">text-align: center;</rendition>
 |   <namespace name="http://www.tei-c.org/ns/1.0">
 |     <tagUsage gi="head" render="#rend.head"/>
 |   </namespace>
 | </tagsDecl>

A new mechanism was put in place with version 2.9:

 | <tagsDecl>
 |   <rendition selector="head">text-align: center;</rendition>
 | </tagsDecl>

The old mechanism is deprecated, and will be withdrawn shortly. The
Northeastern University Library / Digital Scholarship Group has a lot
of TEI files that use the old method that need to be converted. Thus
I wrote an XSLT program to do so. See
https://wiki.tei-c.org/index.php/Render2selector.xslt