port portaudio/portmidi sources from pd 0.46-7. I left the full stable releases in the commits before this so that we can eventually just use those, but atm it's proving to be too complicated to use the stable pa/pm releases.

update configure.in for portmidi sources. Like portaudio, we need to use its build system in the future

update portaudio to pa's recommended stable SVN rev 1919 (used tarball, and one of the docs wrt windows is changed from svn rev 1919, but whatever)

attempt to show the correct directory in a "Save" dialog.  (Still doesn't work for the "Open" dialog.)

stop gap to fix bug with the rendering context disappearing on window close, and stray gui_canvas_getscroll calls trying to access members of the vanished Window object

try to minimize the flashing scrollbars when a canvas becomes visible. (Still getting some flashes for the loadmeter.pd patch)

kludge to account for menubar in patch height. (Might want to rethink the whole idea of menubars in patch windows...)

make the "message" prompt dialog appear in the current window, and default to the canvas id if it's a canvas. This makes it possible to send messages directly to a canvas.

add event listeners for browser window maximize, unmaximize, and resize to call gui_canvas_getscroll

use it to compare performance with the "perfect_parser", which can
decode ISO-8859-1 properly