Rewrote XSLT config codegen in Python

Added new features that weren't doable in XSLT:

- Ability to copy sections of configuration using
  <copy path="XPathExpression"/>. Any recursive
  complexity of copying nodes is supported.

- Checking for cycles in copied nodes to avoid dead loops

- Can include other files recursively using <include file="Filename"/>
  tag.

- Checking for cycles in included files.