add note in todo about potential loss of data when > 4096 bytes of data
are entered into a message box and sent to Pd

* removed a lot of old, commented tcl code
* remove debugging messages
* remove old commented javascript code

refactor dialog_canvas.html to use javascript objects instead of ["name1", "value1", "name2", "value2", etc.] arrays

change fielddesc_getfloat to fielddesc_getcoord so that the (admittedly arcane) scaling/quanta syntax can be used with [draw] methods where it makes sense

do a proper loadbang for canvas fields (needs more testing)