dosemu2 / dosemu2

We have ~300 commits, many of which are bug-fixing, as pre7 was horribly
buggy due to heavy development. As for the newly introduced regressions -
not too much known at this time, except the drop of clang support. We
hope to get clang support back again in the very near future.

Summary of changes:

• Improved hx-extender support so that the win32 version of quake2
  can now work under dosemu2 (in pre7 it was supposed to but didn't).
• Support for external EMS managers like emm286.exe was (partially)
  implemented. As the result, we have a new UMB driver, umb.sys, that
  allows to enable UMB without also enabling EMS, leaving this possibility
  to an external driver.
• New DOSes supported: RxDOS 7.1.x and 7.2, PC-MOS 5.01.
• fossil driver got updates and missing functionality additions.
• Sound stack got updates to reduce the latencies.
• Passing DOS commands via dosemu's cmdline was changed, see man for
  details. Many new possibilities added, like passing environment
  variables and more.
• Some no longer used commands (comline.com, ecpuon.com, ecpuoff.com)
  were removed.
• Dumb terminal mode now handles the charsets.
• Fixes to all regression bugs of pre7 - there were many of them.

We have over 700 commits, mostly targeted on re-introducing and fixing
the features previously supported in dosemu1, and a couple of new ones.
Unfortunately we also have a few regressions.
Summary below.

• Reworks to SDL plugin. The HW-accelerated rendering is now disabled
  by default, as well as the scaling filters, and full-screen switching
  may not work. If you want to use HW-accelerated rendering, try
  $_SDL_swrend = (off). If you want scaling filters or full-screen, use
  'dosemu -X'. We will try to improve the SDL support in future releases.
• HX extender now fully supported, quake2 works!
• Mouse wheel support implemented
• Support booting OpenDOS and some old versions of MS-DOS.
• 2 new keyboard plugins implemented ("stdio" and "tty") to allow dumb
  terminal mode to work without slang library. Selectable with '-kt', '-ks'.
• VGA pass-through in text-mode console is now fully supported. Hope
  no one uses it though.
• Windows-3.1 support is fully re-introduced, and is actually much better
  than in dosemu1. We also provide the mouse driver for windows-3.1 that
  allows the use of the host's mouse pointer:
  https://github.com/stsp/win31-mouse-driver/tree/master/out
• Resurrected basic Windows-3.0 support.
• Foxpro support re-introduced.
• Fixes to SVGA/VESA modes. Support for some missing modes added.
• Many fixes to gfx remapper. The various annoying video artifacts
  should now be fixed.
• SB16 fixes to support sound on more games.
• Mouse copy/paste support is fully re-introduced.
• New $_bootdrive option allows to boot from any drive, not only C.
• Net: IPX and packet driver are fully functional again.
• Lots of build system improvements. We have now the debian build support
  and "make uninstall".
• X fonts are resurrected and provided again.
• Many fixes and improvements: DPMI support is now much more reliable,
  x86 JIT is more reliable, many performance improvements.
• Many updates to interrupt routing code.
• Resurrected emufs.sys.
• Sanitize syntax of lredir2: silly LINUX\FS is no longer needed.

See NEWS for more info.

We have around 500 commits since pre5 with the highlights below:

• KVM is now enabled by default on 64bit builds. A huge speed-up!
• SDL plugin now uses hardware-accelerated texture updates instead
  of the (slow) drawing surface
• virtual modem support is added
• serial port fifos now work again (were broken/unsupported in dosemu2
  but worked in dosemu1)
• DPMI context switching is rewritten for speed-up, using a new
  linux kernel extensions and the code from libtask and libpcl
• default DPMI memory size enlarged to 128Mb, which is enough for
  all known DOS programs
• new builtin command system.com is added that runs DOS commands
  specified via the unix env vars. Similar functionality in unix.com
  is kept for compatibility.
• DOSDRIVE_D var is removed. Use new DOSDRIVE_EXTRA variable.
• mouse driver got a huge overhaul for improved robustness in non-grab mode
• winos2 mouse extension is implemented for better support of the OS/2
  mouse driver under windows-3.1
• middle mouse button is now supported (was broken)
• dosdebug fixes
• many fixes to SDL plugin
• the home dir is no longer exposed to DOS by default. Use -home if you
  need this.
• added -cdrom option that tries to mount the cdrom and expose it to DOS
• $_hdimage option can now embed environment variables
• many performance bottlenecks were located and fixed
• many fixes and updates

See NEWS for more info.

• SDL video backend is now default, which means a GPU-accelerated rendering
• lredir command was deprecated, use lredir2 with the new syntax
• unix.com syntax was slightly changed
• new tool sound.com is added to change sound and MIDI parameters at run-time
• LPT2 is now pre-configured to print to PDF files
• Added preliminary support for old MS-DOSes (>=3.3) and some DR-DOSes
• many improvements to dosdebug
• use logarithmic volume scale for sound
• Preliminary KVM support - a very fast execution on 64bit machines.
  Should be manually enabled in config for now.
• Many regressions fixed
• Added valgrind support, which allowed to find many obscure bugs
• Work-arounds to support the newer fluidsynth for MIDI
• More versions of libao are supported for sound (each having its own bugs).
  This is good when SDL2 is unavailable.
• munt support for mt32 (you need to download Roland ROMs yourself)
• built-in backtracer is added for a better crash logs.
  Used if gdb is not installed.
• clang is now supported to compile dosemu2