This brings msg box back to the same performance it had before $0 expansion
was added as a feature to message boxes.

The first implementation relied on calling canvas_setcurrent and
canvas_unsetcurrent in the message box methods. This added a malloc/free
for each message box method call.

Instead this implementation caches the msg box glist in the t_messresponder.
That is available as the target parameter in m_binbuf. Unfortunately, we
have to add a parameter to binbuf_realizedollsym. Since that's a public
function we have to break out the new param into binbuf_dorealizedollsym.

Jonathan Wilkes authored Feb 09, 2018 and Albert Gräf committed Feb 10, 2018

Also fix a type mismatch in dropdown widget (g_text.c) and add
an error check in ALSA audio (s_audio_alsamm.c).

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

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.

This makes it possible to define an editable viewport outside of which the
contents are clipped.

One big benefit is that the getrect routine doesn't need to fetch the bboxes
of the shapes inside the viewport. It just needs the svg width, height, x,
y, and parent transform. It's also possible to add an optimized branch if
there is no parent transform specified.

One drawback is that the HTML5 method getBBox() includes the clipped content
in its calculation. That means the user will get scrollbars even though the
[draw svg] is clipping the contents which cause the scrollbars. Hopefully we
can just work around this by adding a "scrollbars" method for canvases to
just turn them off altogether.

Code for an experimental [draw array] is also added here. Combining it with
the viewport of [draw svg] will make it possible to interact with arrays of
widgets without the performance penalty normally associated with mouse
motion on Pd canvases.

Also:
* fixes some display bugs in certain cases for [draw image] and
[draw sprite]
* adds a default png for both [draw image] and [draw sprite] if none are
given

make [declare -lib] handle absolute paths (and namespace-prefixed paths) consistent with object boxes

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

fix "stale pointer" bug when re-opening a subpatch on a scalar that has an event bound to it. The bug was that the scalar symbol wasn't getting unbound because scalar_vis wasn't getting called.

fix #119: store canvas title for later use. This will properly display the title for a dirty canvas in the case where the Pd patch is mutated with a loadbang (and properly other cases, too)

These bugs were discovered via static code-analysis
https://scan.coverity.com/projects/pure-data-pure-data
(The CID numbers are the "Coverity IDs" used to identify the various bugs)

- Don't free binbuf within glist_readfrombinbuf (CID:74871)
- it must be deleted by the caller
- Initialize sockaddr_in (CID:74861,74862,74863,74866)
- Initialize indelay/outdelay (CID:74864,74865)
- Initialize device-arrays (CID:74853,74854,74855,74856)
- Closing unneeded sockets (CID:74827)
- Initialize sockaddr_in (CID:74860}
- Close file-descriptor if the soundfile is unparsable (CID:74822,74823)
- Close file-handle in cleanup (CID:74816)
- Call va_end() when handling variadic args (CID:74872)
- Added missing break (CID:74800)
- Prevent NULL-dereferences (CID:74792,74793)
- Size checks when copying into string buffers (CID:74844,74845,74846,74847,74849)
- Freeing no-more used storage (CID:74832)
- Fixed code block (CID:74806)
- Initialize sockaddr_in (CID:74860)
- Initialize array-values to 0 (CID:74867)
- Free allocated memory (CID:74813,74830)
- Removed allocation of unused memory
- Use pd_free() to free templates (CID:74814)
- template_free() does not free the entire structure (it misses the pd_new() part)
- initialize variable (CID:77865)
- Prevent NULL-pointer dererencing (CID:77864)
- Free heap-allocate binbuf after use (CID:74833)

port a031e3b64f725c8cb3274b5ef3ff0e27a36222f5 from Pd-l2ork: fixed parsing of @pd_extra and @pd_help names in filenames

port 9ab1b10476bca7e3998d5bf907296979dfc6e558 from Pd-l2ork: fixed regression where canvaslist was not properly stored

port e814c4d586c52fe9a6a39a58947df1870e04e986 from Pd-l2ork: updated load/init/closebang to match the new spec

*Reverted http://sourceforge.net/p/pure-data/pure-data/ci/97851b3c44b2b3839069928d90ca6185de4455c5/ as it disables ability to address abstractions via scripting (needs further testing to figure out why was this disabled in the first place and then later reverted by Miller)
*fixed way of vis-ing GOP-enabled abstractions via script

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

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

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