ChangesListSpecialPage and subclasses: Reorder functions

No functional nor cleanup changes, just reordering. This should
make further refactoring (and reviewing it) easier.

In ChangesListSpecialPage placed them in "call-graph" order
instead of somewhat randomly.

In subclasses placed ChangesListSpecialPage functions first in the
same order, feed-related things later, and internal functions last.

Change-Id: I0cccfdb7c5ecd99a92d09d835211153279d71846
Merge "ChangesListSpecialPage and subclasses: Reorder functions"