use filebrowsebutton from lib
new dir structure for sandbox code
change properties and position of FBB
set background to system style
Merge branch 'master' into filebrowsebutton
clean up style and properties flags
add list filters, avoid empty updates
Merge remote-tracking branch 'origin/filebrowsebutton' into filebrowsebutton
move argparsing to main(), adjust __init__()
use printf-style for output
code cosmetics
fix indenting
documentation, PEP8 conformance
variable renaming
remove filebrowsebutton, more handlers, expand grid
first working prototype actually running the calculation
add todo
add TODOs, fix variable name
add documentation for build_filament_mask()
add documentation for largest_dist_idx()