sprites: add Korp's minigun edit. (#1041)

* sprites: add Korp's minigun edit.

I've shrunk down the flash to make it more consistent with the pistol and PEW (it's actually still much too big relative to the pistol and shotgun but at least it doesn't look jarringly distracting and obscuring the target), and made a few tiny adjustments to the weapon body to deal with some palette issues.

* sprites: fix CHG* offsets.

buildcfg.txt

@@ -2185,10 +2185,10 @@ BPAKA0	11	26
 BROKA0	27	20
 CANDA0	8	15
 CBRAA0	14	61
-CHGGA0	-105	-114
-CHGGB0	-105	-121
-CHGFA0	-125	-83
-CHGFB0	-125	-98
+CHGGA0	-108	-117
+CHGGB0	-108	-121
+CHGFA0	-127	-95
+CHGFB0	-129	-111
 CLIPA0	4	12
 COLUA0	9	45
 CSAWA0	22	20