add default savefig directory
replace tabs with spaces
explicitly missing key or empty str signals to use cwd
PEP8
Implement savefig.directory for tk gui
fix comment in gtk FileChooserDialog: does *not* remember last selected file/directory
Implement savefig.directory for gtk gui
Implement savefig.directory for gtk3 gui
Update CHANGELOG with savefig.directory feature
Split line
Update what's new with savefig.directory feature