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.
whitespace
refs https://bugzilla.mozilla.org/show_bug.cgi?id=946461 - tidying vagrant build dependencies in dxr.pp
Merge: stop pulling in all of Firefox's build-deps. Fix bug 946461.