fix up Windows-specific build script to just rsync the pd/doc directory. At some point we need to use makefile.in for Windows just like Linux and OSX do...

keep midr-mjpeg.mov in pd/doc/media, but remove all the copies of external media files. There aren't any references to those copied files in any of the docs, so they are useless. This means the root "doc" directory is now gone.

repo cleanup: remove tcl/tk build infrastructure and scripts, old patches, automated build scripts for pd-extended, old gui plugins, and unnecessary install-time dependencies

port all relevant externals to the new loadbang interface. Unfortunately it has some #defines hidden in g_canvas.h, so we port that macro individually to each affected library.

improvements to the dropdown atom: use scrollbar when menu size exceeds the viewport size. Also, add keybindings for Enter, Escape, Space, arrow keys, and navigating options by matching keypresses to the first character

sys_expandpathelems: replacement for @pd_help should be the last element on the path, not the first.

Simplify the pipeline in sys_initloadpreferences() so that we read the preferences directly using plutil now.

This is done by importing the config data using 'defaults import' in
one go, which is *much* faster than the previous implementation which
invoked the shell to run 'defaults write' for each individual key.

Intelligent patching mode 4 often just always prefers option A (outgoing
connections). But if the user actually wants option B (incoming connections),
he can't get it because option A was chosen. This is confusing, which is why
mode 4, while very useful if it works as intended, can be rather difficult to
use right now.

We therefore now take into account the status of the ctrl modifier, which
simply reverses our choice of option A or B, so that the user now has a way of
getting option B even if option A is preferred (and vice versa). If the ctrl
modifier isn't pressed, mode 4 works exactly as before, so this change is
fully backwards-compatible.

fix dropdown menu on Windows-- it uses nw.js 0.14.7 which didn't include the "forEach" method for DOM nodelists