Add more register #defines to ANTIC header file

Add more register #defines to ANTIC header file

 * DMACTL - playfield size, DMA access, PMG resolution
 * CHACTL - inverted text, inverse effects
 * NMIEN

Also, added #define equivalents for Display List mode line instructions
based on Atari 8-bit OS (aka Atari BASIC "GRAPHICS" command) values
(e.g., "DL_GRAPHICS0" == "DL_CHR40x8x1").

Added some more documentation in the comments.

Added macros with assembly language for the start/end of Display List
Interrupt (DLI) functions.