Refactored normal doors to use a lookup table. Now the door table is <4k

Fixed graphics between HC/Sewers and cross dungeons.
Added base work for spiral staircases in HC/Eastern. (More data needed for other dungeons.)
Added new region to deal with push blocks in Sewers Secret Room
Refactored asm to be in multiple files.

asm/gfx.asm

@@ -0,0 +1,47 @@
+GfxFixer:
+{
+    lda $b1 : bne .stage2
+    jsl Dungeon_InitStarTileCh
+    jsl LoadTransAuxGfx
+    ;jsl Dungeon_LoadCustomTileAttr
+    jsl PrepTransAuxGfx
+    lda #$09 : sta $17 : sta $0710
+    inc $b1
+    rtl
+    .stage2
+    cmp #$01 : bne .stage3
+    lda #$0a : sta $17 : sta $0710
+    inc $b1
+    rtl
+    .stage3
+    jsl Palette_SpriteAux3
+    jsl Palette_SpriteAux2
+    jsl Palette_SpriteAux1
+    jsl Palette_DungBgMain
+    jsr CgramAuxToMain
+    stz $b1 : inc $b0
+    rtl
+}
+
+CgramAuxToMain: ; ripped this from bank02 because it ended with rts
+{
+    rep #$20
+    ldx.b #$00
+
+    .loop
+    lda $7EC300, X : sta $7EC500, x
+    lda $7EC340, x : sta $7EC540, x
+    lda $7EC380, x : sta $7EC580, x
+    lda $7EC3C0, x : sta $7EC5C0, x
+    lda $7EC400, x : sta $7EC600, x
+    lda $7EC440, x : sta $7EC640, x
+    lda $7EC480, x : sta $7EC680, x
+    lda $7EC4C0, x : sta $7EC6C0, x
+
+    inx #2 : cpx.b #$40 : bne .loop
+    sep #$20
+
+    ; tell NMI to upload new CGRAM data
+    inc $15
+    rts
+}