Make config.trees order by position in config file. Fix Bug 969873
Default Tree To Route
Added Default Tree Option
Sort config.trees alphabetically for switch_tree menu
Sorting Trees Alphabetically for Switch Tree Menu
Update config.py
Make sure that default_tree is defined
Route To The Default Tree First
Patch up a few idioms.
Bump format version, since we need the DEFAULT_TREE key in config.py.
Merge in better build-order handling for trees. Close #246. Fix bug 969873.

Now you control the build order by ordering the sections in the config file. The Switch Tree menu, however, always lists trees in alphabetical order.