feat(kernal): $E5B4, $EA24, and $ECF0 at their well-known addresses

cc65's C64 runtime and ip65 call past the jump table: $E5B4 takes the first
key from the keyboard buffer (cgetc), $EA24 points USER at the colour RAM of
PNT's line (cursor positioning), and $ECF0 holds the low bytes of the screen
lines' addresses (ip65's VT100 code), as Mapping the Commodore 64 describes
them. vicii_init's work moves out of $E5A0-$E5C8 to free $E5B4, and on the
standard layout PNT and USER are worked out through the routine at $EA24.

src/kernal/init/vicii_init_registers.s

@@ -0,0 +1,52 @@
+;; #LAYOUT# STD *        #TAKE
+;; #LAYOUT# CRT KERNAL_0 #TAKE
+;; #LAYOUT# M65 KERNAL_1 #TAKE
+;; #LAYOUT# *   *        #IGNORE
+
+;
+; The VIC-II set-up of vicii_init (e5a0.vicii_init.s), moved out of $E5A0-$E5C8
+; so that $E5B4 is free
+;
+
+
+vicii_init_registers:
+
+	; Clear everything - turn off sprites (observed hanging around after
+ 	; running programs and resetting), etc.
+
+	lda #$00
+ 	ldx #$2E
+@1:
+ 	sta __VIC_BASE, x
+ 	dex
+ 	bpl @1
+
+	; Set up default IO values
+	; - [CM64] page 129       - VIC_SCROLY
+	; - [CM64] pages 140-144  - VIC_SCROLX
+	; - [CM64] pages 145-146  - VIC_YMCSB
+
+	lda #$1B                           ; according to [CM64] page 137 some software assumes oldest bit is 0
+	sta VIC_SCROLY
+	lda #$C8
+	sta VIC_SCROLX                     ; 40 column, etc.
+	lda #$14
+	sta VIC_YMCSB
+	lda #$0F
+	sta VIC_IRQ                        ; clear all interrupts
+
+	; We use a different colour scheme of white text on all blue by default,
+	; but brand-specific color scheme can also be enabled
+
+	lda #CONFIG_COLOR_BG
+	sta VIC_EXTCOL
+	sta VIC_BGCOL0
+
+	; Setup default I/O devices
+
+!ifdef CONFIG_IEC {
+	jmp clrchn_reset
+} else {
+	jmp CLRCHN
+}
+