fix regression with [pd] not respecting new box dimensions when renaming to [pd foo]. Also, comment out more sys_vgui calls in g_canvas.c

first try at get the copyfromexternalbuffer logic ported. This allows to paste Pd source code into a patch

comment out some sys_vgui calls which are _probably_ no longer necessary (plus extra comments saying as much)

update open dialog window height/width/font/fontsize for iemguis as they are resized/repositioned with the mouse

fix iemguis and canvas scalehandle to track mouse position instead of delta-- this fixes a bug when the mouse goes below the minimum dimensions. Plus, some more cleanup of the scalehandle code

restore the ability to show multiple iemgui label handles at once, and use class instead of id to identify them

use <dialog> modal instead of javascript prompt. Also, port some changes from Vanilla to allow closing window immediately after saving

remove pdtk_check_scroll_on_motion for the time being. (Not sure it's needed, but can revisit if necessary)

removed the array listview code from g_array.c.  Seemed pretty straightforward to prune, but should probably test to make sure there aren't any obscure regressions

add boilerplate for keeping track of toplevel Pd canvases in the GUI. While the GUI knows all the open windows, it can't tell the difference between a Pd toplevel and a subpatch. I'm not sure why the difference is important, but this interface supplies that info to the GUI.

further refined legacy mode to match both iemgui and graph-on-parent objects.

second draft of iemgui handles--- still some bugs when switching between canvas gop rect and iemguis

made nbx scaling less wonky. It's still a bit wonky, but maybe that's just a function of the font resizing algo and the fact that width is constrained to character width