v1.2.0

Added

• canvas: render frames from Rust straight into an mIRC picture window, through mIRC's
  /drawdll (mIRC 7.83 and later). export_draw! exports functions of the form
  fn(Draw) -> impl IntoUpdate; Draw and Canvas give access to the window's bitmap,
  Image holds 0x00RRGGBB pixels to copy in (Canvas::draw, draw_at), and Update
  says what mIRC should redraw (Redraw, Area, Skip, Default). draw_command builds
  the /drawdll command for one of your own exports, quoting the DLL's path.
  • Fast: in mIRC 7.85 a 1920 × 1080 frame takes about 2 ms to copy in and a 398 × 264
    frame 0.25 ms, against about 6 ms and 11 ms for drawing a BMP with /drawpic (before
    counting writing the file).
  • A picture window can be a toolbar button's picture. The button doesn't follow the
    window, so refresh it with /toolbar -p name @window after each frame; both commands
    fit in one mirc::command string.
  • Calling a drawing export any way other than /drawdll does nothing; a panic halts the
    script.
  • Tested in mIRC 7.85: each Update variant, a panicking export, a DLL path containing a
    space, and 30, 60 and 120 frames per second into a toolbar button, with every frame
    sent reaching the export.
• dll_path(): the DLL's own full path, for commands that name it, such as /dll -u to
  unload itself from a worker (the worker keeps the DLL mapped until it returns).
• Notes on drawing into a toolbar button in the README (the 256 pixel limit, sizing to the
  toolbar with TB_GETITEMRECT, what it costs mIRC), from m_nyancat, a separate project
  that animates Nyan Cat in mIRC's toolbar with canvas.