Remove tidyHtml from the template generation tools.

Remove tidyHtml from the template generation tools.

While nice, It introduces several problems:

 * any syntax errors at all in the translation text causes a blank
   translated text file to be produced. Without any error code.

 * automatically downgrades the HTML content-type meta to "us-ascii"
   despite the input and output both actually being UTF-8

 * added dependency for building.

It's used automatically by the translate toolkit from 1.5.0 so
needs to be expicitly disabled when present.