v0.1.2

Added

• A headless mode has been added. This allows Erc to run without graphics or
  sound. In headless mode, Erc is able to watch and logs various computer
  states, memory addresses, registers and so forth. Headless mode is intended
  to support black box testing.
• A miniature assembler was built as a standalone command (erc-assembler)
  which is used to build one-off disk images for black box testing. The
  assembler compiles an input program and writes the program data into the
  first track of the disk. Anything more than that won't work, as the Apple's
  first stage boot loader will only read the first track into memory.
• Added a large cohort of black box tests to support the new headless mode;
  the MOS 65c02 CPU; keyboard shortcuts; the inline interactive debugger; and
  40-column TEXT mode. In all we have over 280 black box tests now.
• Support ZPI (zero page indirect) address mode for the MOS 65c02 CPU.

Fixed

• Carry flag is now set if the decimal accumulator is not negative after a
  subtraction. The previous behavior (setting carry if the result was >= 0)
  wasn't correct in that context.
• Text page 2 ($0800-$0BFF) and display page 2 ($4000-$5FFF) are properly
  mapped for graphic display. Previously they had not been, which meant that
  updates to those areas might not cause a screen rerender. One way I've seen
  this problem is a static text screen where some characters are missing.