Add the mc64 configuration, the Firmware of arnitech's mc64

A copy of the c64 configuration with its own ID ($6D), the brand "MC64",
and BCD_SAFE_INTERRUPTS off, plus its Makefile targets
build/kernal_mc64.rom and build/basic_mc64.rom, made the same way as the
c64 ones. NOTICE says who modified the fork, when, and what changed.

src/,,config_mc64.s

@@ -0,0 +1,130 @@
+
+;; #CONFIG# ID $6D ; should be 1 byte, different for each config file!
+
+;
+; Please read CONFIG.md before modifying this file!
+;
+
+; Idea:
+; The Firmware of arnitech's mc64 computers, a Minecraft mod
+; Same as the 'c64' configuration, except:
+; - the banner names mc64
+; - BCD_SAFE_INTERRUPTS is off, for IRQ entry timing closer to the original
+
+
+
+; --- Hardware platform and brand
+
+;; #CONFIG# PLATFORM_COMMODORE_64      YES
+;; #CONFIG# BRAND_CUSTOM               "MC64"
+
+
+; --- Processor instruction set
+
+;; #CONFIG# CPU_MOS_6502               YES
+;; #CONFIG# CPU_DTV_6502               NO
+;; #CONFIG# CPU_RCW_65C02              NO
+;; #CONFIG# CPU_WDC_65C02              NO
+;; #CONFIG# CPU_WDC_65816              NO
+;; #CONFIG# CPU_CSG_65CE02             NO
+
+
+; --- Memory model
+
+;; #CONFIG# MEMORY_MODEL_38K           YES
+;; #CONFIG# MEMORY_MODEL_46K           NO
+;; #CONFIG# MEMORY_MODEL_50K           NO
+;; #CONFIG# MEMORY_MODEL_60K           NO
+
+
+; --- IEC bus configuration
+
+;; #CONFIG# IEC                        YES
+;; #CONFIG# IEC_DOLPHINDOS             NO
+;; #CONFIG# IEC_DOLPHINDOS_FAST        NO
+;; #CONFIG# IEC_JIFFYDOS               NO
+;; #CONFIG# IEC_JIFFYDOS_BLANK         NO
+
+
+; --- Tape deck configuration
+
+;; #CONFIG# TAPE_NORMAL                YES
+;; #CONFIG# TAPE_TURBO                 NO
+;; #CONFIG# TAPE_AUTODETECT            NO
+;; #CONFIG# TAPE_NO_KEY_SENSE          NO
+;; #CONFIG# TAPE_NO_MOTOR_CONTROL      NO
+
+
+; --- Sound support
+
+;; #CONFIG# SID_2ND_ADDRESS            NO
+;; #CONFIG# SID_3RD_ADDRESS            NO
+;; #CONFIG# SID_D4XX                   NO
+;; #CONFIG# SID_D5XX                   NO
+;; #CONFIG# SID_D6XX                   NO
+;; #CONFIG# SID_D7XX                   NO
+
+
+; --- Keyboard settings
+
+;; #CONFIG# KEYBOARD_C128              NO
+;; #CONFIG# KEYBOARD_C128_CAPS_LOCK    NO
+;; #CONFIG# KEY_REPEAT_DEFAULT         NO
+;; #CONFIG# KEY_REPEAT_ALWAYS          NO
+;; #CONFIG# KEY_FAST_SCAN              YES
+;; #CONFIG# JOY1_CURSOR                YES
+;; #CONFIG# JOY2_CURSOR                YES
+
+;; #CONFIG# PROGRAMMABLE_KEYS          YES
+
+;; #CONFIG# KEYCMD_RUN                 "\5FL"
+
+;; #CONFIG# KEYCMD_F1                  "@8$"
+;; #CONFIG# KEYCMD_F2                  "LOAD"
+;; #CONFIG# KEYCMD_F3                  "@9$"
+;; #CONFIG# KEYCMD_F4                  "RUN:"
+;; #CONFIG# KEYCMD_F5                  "@10$"
+;; #CONFIG# KEYCMD_F6                  NO
+;; #CONFIG# KEYCMD_F7                  "@11$"
+;; #CONFIG# KEYCMD_F8                  NO
+
+;; #CONFIG# KEYCMD_HELP                "LIST"
+
+
+; --- Screen editor
+
+;; #CONFIG# EDIT_STOPQUOTE             YES
+
+
+; --- Software features
+
+;; #CONFIG# PANIC_SCREEN               YES
+;; #CONFIG# DOS_WEDGE                  NO
+;; #CONFIG# TAPE_WEDGE                 NO
+;; #CONFIG# TAPE_HEAD_ALIGN            NO
+;; #CONFIG# BCD_SAFE_INTERRUPTS        NO
+
+
+; --- BASIC features
+
+;; #CONFIG# ORIGINAL_UNPATCHED_BASIC   YES
+;; #CONFIG# TRANSCENDENTAL_FUNCTIONS   YES
+
+
+; --- Eye candy
+
+;; #CONFIG# COLORS_BRAND               NO
+;; #CONFIG# BANNER_SIMPLE              YES
+;; #CONFIG# BANNER_FANCY               NO
+;; #CONFIG# SHOW_FEATURES              YES
+
+
+; --- Debug options
+
+;; #CONFIG# DBG_STUBS_BRK              NO
+;; #CONFIG# DBG_PRINTF                 NO
+
+
+; --- Other
+
+;; #CONFIG# COMPRESSION_LVL_2          NO