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This fixes issues where "leftovers" from the previous mode would
remain in a new screen mode.

Also, we don't need to use pointers for the scaling.

I really need to do a sweep through and update all the aspect
ratios now that the data actually matters.

1) Initialize the r2y array for xBR so it actually works.
2) Add a vertical (only) interpolation scaler for aspect ratio enforcement
3) Add a simple muliplier scaler, so that can be removed from x_event.c
4) Use a new graphics buffer free list, which allows tracking last
   drawn screen instead of last bitmap rectangle, removing various hacks
5) Share the Y'CbCr <-> R'dG'dB'd tables between xBR and scale.c

Uses "pointyscale" for x3 and x5
Uses xBR from FFmpeg for x2 and x4
HQx is also included, but unused as it's too slow at x4.

There are a number of conio changes in here too... too many to list.  Check
the diffs if you actually want to know what changed.

There's still some shittiness with the keypad, but nobody really knows how
that works anyway.

Add support for scroll "buttons" (buttons 4 and 5).

We don't need a unicode -> cpchar with ext...
We do need codepoint -> cpchar with and without ext.

getcliptext() and copytext() (ie: copy/paste) now work on UTF-8 strings.
Not tested on Win32 yet.

This is planned to work with the built-in fonts... no real idea how to
make this work with dynamic fonts at this time.

We'll also need a line drawing set thing ala curses, but I'll worry about
that when/if I update uifc32 for unicode.

center the xim in the resulting window and fill the rest with black.

Resize the xim if the window isn't scaled.

The xim wasn't scaled to the new size (ever)

If this doesn't fix the copy/paste issues nelgin was having, nothing will.

Should fix issue nelgin is having.

Add UTF-8 copy/paste support to X11 mode.

Avoid gratuitous xim reallocations (not a bug)
Avoid gratuitous redraws (not a bug)
Avoid posting and waiting on a semaphore from the same thread (ehhhh....)
After blocking on XNextEvent(), drain all X events in the queue (not a bug)

bitmap_init_mode().

Thanks Coverity!

1) Send updates in 16-lines chunks rather than a single large update.
2) Keep the last screen rectangle around, and compare against it.
3) pre-calculate values.

Too lazy to write me own fls() basically.

Set all unused bits 'cause they may be transparency.