Also introducing (not a complete list):

* (acme) REP file based hypervisor debugging
* HDOS call tracking
* HDOS virtualization alpha stage
* System initialization changes
* Better initial D81 mount tracking
* More sane CLI/options (eg single rom option
  to load ROM, no need extra -forcerom and other
  bizarre things)

* Reogranization some of the UI menu
* Provide new functionalities

The heart of the `hyppo` branch, that is using a new and decent enough
hyppo. Also it required many changed here and there to support the new
scheme, like using an initial ROM (open-ROMs) pre-filled the memory
along with other utilities.

SDL on OpenBSD seems to have problem with SDL_GetBasePath(). So as a
workaround I've put some code to use the absolute path from argv[0] or
the getcwd() result + relative path from argv[0] in this case.
Meanwhile, I had to realize that it needs to passing argv and argc to
xemu_pre_init() function anyway, so I can simplify some logic needed to
pass those again for the xemucfg_parse_all(). However this also means,
that I had to modify every emulators according to this API. I also put
some slight modification into MEGA65 emulator's matrix mode so things
can be queried to be able to check.

Thanks to rt.fm on Discord for testing Xemu on OpenBSD + spotting this
SDL2 bug.

* Respecting palette(16) pointer in case fgcolor is selected

Xemu allows to create brand new D81 (and then mounting it). There was a
minor difference though with the D81 created, compared to the one
created with VICE's c1541 tool: the disk-id should be stored actually at
three different places, while Xemu updated the disk image at only one
location. Though possibly it does not create any problem, let's perfect.
Now the created D81 with c1541 and Xemu (given by the same disk name and
disk id) are identical at binary level.

At this stage it's primarly useful for using closed-ROM's DLOAD"..",U12
feature, so with HDOS virtualization enabled, it's possible to load a
file outside of a D81 from BASIC65 directly.