Port pd-l2ork upstream commits from Dec 7, 2015 improving the handling of $ substitutions in GUI elements. Also fixes #195.

cleanup iemgui dialog form names, replacing dashes with underscores. Fix stray bugs in canvas dialog, and clean up css selector names

stop using "x" for sending iemgui colors-- while it has a precision formatter, it doesn't have a maximum size formatter (and it can't because 64-bit archs need the larger values)

add my_canvas_class conditional in g_editor.c to disallow resize anchor, since it abuses an extra label handle for resizing.

* check canvas visibility in iemgui_displace
* check visibility before updating scroll in canvas_dofont

*fixed a bug/regression reported by Liam Goodacre regarding label inside GOP when it exists frame and needs to reapper (due to script-based repositioning) would crash pd-l2ork. See http://disis.music.vt.edu/pipermail/l2ork-dev/2016-January/000811.html for more info.

Death to tcl Part 1: remove all sys_vgui messages that match the following constraints: 1) code is not annotated; 2) has a corresponding gui_vmess replacement; or 3) old commented code that is obviously no longer needed

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

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

 *added legacy option for iemgui objects. Starting pd-l2ork with -lega…

…cy flag positions iemgui objects in their old, vertically inconsistent locations for the sake of retaining complete backwards compatibility.

*added sys_legacy global for inclusion of other potential legacy breakages that may develop later.

implemented iemgui "pos" method