Features with page manager components are perpetually overridden

When exporting page handlers, it assigns each pane a "new-*" ID.
The counter for that ID is statically cached, since only one is exported at a time.

However, when running features-list, it renders all at once, which never resets the counter.

In code:

Feature 1:
  Variant 1:
    new-1
    new-2
  Variant 2:
    new-1
    new-2
Feature 2:
  Variant 1:
    new-1
    new-2
  Variant 2:
    new-1
    new-2

Generated for comparison:

Feature 1:
  Variant 1:
    new-1
    new-2
  Variant 2:
    new-3
    new-4
Feature 2:
  Variant 1:
    new-5
    new-6
  Variant 2:
    new-7
    new-8

This resets that ID when appropriate.

Note, the second example in #1 with the sequential ids is wrong. The patch makes the generated code match the default code.