Pressing Shift+A (Add > Single Bone) in Armature Edit mode will now
align the bone with the world Y-axis instead of the Z-axis. This makes
the bone's axes align with the world axes (instead of aligning bone-Y
with world-Z).
This only applies when using 'Align To: World' in the Editing
preferences. 'Align To: View' still behaves as before, and 'Align To: 3D
Cursor' behaves like 'World' because that option was never handled
anyway.
Align the default bone that's added to the Armature you get with
'Shift-A > Armature' to the Y-axis. When the alignment is set to 'World'
this will actually align the bone's axes with the world axes.
Note that the 'View' alignment option already aligned the bone along the
Y-axis, so the code has been simplified a bit.