Defines starting with `i' in jagdoom

• IDWORD src/jagonly.c:1414
• INFRATICS src/doomdef.h:326
• INTERNAL_BUFFER_SIZE src/sound.h:6
• INTERNAL_MASK src/sound.h:7
• INTERNALQUADS src/soundst.h:34
• INVERSECOLORMAP src/r_local.h:35
• INVISTICS src/doomdef.h:325
• INVULNTICS src/doomdef.h:324
• IRONTICS src/doomdef.h:327
• ITEMQUESIZE src/p_mobj.c:9
• ITEMSPACE src/o_main.c:8
• IVALX src/in_main.c:8
• IVALY src/in_main.c:9