Version 1.2u1, 2024/01/02:
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- Support original size (125x147), 2x (250x294), and 4x (500x588).
- Recreate the 250x294 graphics by resizing without interpolation,
  to give a "crisp and pixellated" look rather than blurry.
- Change the build system back to make. This project is so simple
  that I don't see any benefit in using cmake.
- Add icons and .desktop files.
- Tell the window manager not to allow resizing the window. The
  app can't resize anyway, so trying to make the window bigger just
  results in a confusing mess. Making it smaller works, but parts
  of the UI get cut off so it's unusable. Probably, tiling window
  managers will ignore this (not much I can do about that).
- Fix a few -Wall warnings.
- Fix a segfaulting bug. To reproduce, start up the old hcalc and
  press Backspace 6 times (or so; eventually it will crash).
- Add command-line options to control the window size (-small -medium
  -large).
- Add command line options to control the starting number base (-hex,
  -dec, etc).
- Add a man page. There was no documentation at all.
- Change "q" to quit, to uppercase Q or control-Q. I kept exiting when
  trying to type a 1.
- Get rid of ^C = quit keystroke.
- Add ^C and ^V keystrokes for copy and paste. Now hcalc is fully
  functional without using the mouse.
- Add modulus operation. % key, or right-click on / button.
- Add C as a synonym for Escape (CLR key).
- Add Delete as a synonym for backspace (DEL key).
- Fix a bug: stop allowing hex digits a-f when in decimal mode.
- Add ~/.hcalc.cfg, which holds the state of hcalc. Written on exit,
  read on startup. Also add -default arg, to prevent reading this.
- Add -quiet option to silence the X bell.
- Allow changing the window size while running (toggle between the 3
  sizes).
- Add a 'make install' target, which will install the binary, icons,
  man page, and .desktop file (with DESTDIR support for packagers).
- Show "err" for floating point error (e.g. divide by zero), and wait
  for the user to press CLR to continue.