FIX TreeModel: handle absence of default field value
FIX load.fiff:  load sqd files
FIX setup:  work with Canopy distribution

- py2app -A
- bash command
ENH:  combine NDVars with SourceSpace dim
TEST:  add some tests
DOC
ENH WxTerm:  don't print invalid interpreter intro
ENH Factor:  sort .cells naturally
ENH Makefile:  add `clean-pt` option to remove *.pyo and *.pyc files