~nch/glue

remove some older experiment files
add sdl2 scheduler
implement drag and drop using reactive programming (rxpy) and a relational table structure (pandas)
use pandas instead of my bespoke tables for now
different approach -- represent everything as tables -- so far graph construction works
low level implementation of the goal
yet another attempt... still broken with fib
WIP this seems(?) to be working
WIP attempt with generators
WIP got some basic Lucid-ish code running - one is still broken
a few more dataflow attempts
implemented rest of arrowlets
initial arrowlets
clean up node editor code
more table features
add table implementation
add draggable labels