use canvas_getrootfor instead of glist_getcanvas, guarantee editor gets created when reloading abstractions

remove redundant call in g_mycanvas.c and filter repeated label updates if
the label hasn't changed as in Pd Vanilla

However, we still need to figure out if we want to supress gui_canvas_getscroll
when suppressing the scrollbars. Currently it still gets called, which will
adjust the viewport to make objects at negative indices visible. I think
instead we want to anchor the viewport to 0,0 at top left and supress those
calls to get a nice speedup in the GUI.

commit: 3f92d75115d8e8a2ab5a8234be0326b6391ac378

(tcl errors on closing a patch in which a scalar was getting a deferred
update, usually I think because of an array).

commit: 418c7380b066db065dcc8a3315f4a6ca61f7bf1c

just leave the title unchanged you don't get "save as" action again on
next save

commit: 470032130e2b0135b97151d719c4706d68f3c380

We ignore the reversion and workaround in a later vanilla commit for an
OSX tk issue that doesn't apply to nw.js