FIX:  supply subjects_dir in test
ENH:  add split_label() function
ENH assert_labels_equal:  issue message specifying mismatch
FIX Label.__add__:  add subject for new label
DOC:  whats_new
OPT split_label():  determine normal based on coordinate on sphere

add fs_like argument for Freesurfer backwards compatibility
FIX:  use py-2.6 compatible syntax
STY:  remove unused import
STY
ENH:  add Label.split() method
Merge pull request #1085 from christianmbrodbeck/split-label

Split label