sprites: adjust minigunner perspective. (#889)

Also changes the colour of the bullet belt to better match the current minigun pickup sprite.

Removes some lines of empty pixels and lowers the 4/6 sprites to better match the other angles.

buildcfg.txt

@@ -1224,30 +1224,30 @@ CPOSA1	18	52	; heavy weapons guy
 CPOSB1	18	52
 CPOSC1	17	52
 CPOSD1	18	52
-CPOSE1	15	52
-CPOSF1	15	52
-CPOSG1	16	52
+CPOSE1	13	52
+CPOSF1	13	52
+CPOSG1	16	53
 CPOSA2A8	16	51
-CPOSB2B8	18	52
-CPOSC2C8	16	51
-CPOSD2D8	16	52
-CPOSE2E8	33	52
-CPOSF2F8	42	52
-CPOSG2G8	22	52
-CPOSA3A7	18	52
-CPOSB3B7	24	52
+CPOSB2B8	18	53
+CPOSC2C8	16	52
+CPOSD2D8	16	53
+CPOSE2E8	26	52
+CPOSF2F8	30	52
+CPOSG2G8	23	52
+CPOSA3A7	17	52
+CPOSB3B7	21	52
 CPOSC3C7	13	52
 CPOSD3D7	21	52
-CPOSE3E7	30	52
-CPOSF3F7	40	52
+CPOSE3E7	33	52
+CPOSF3F7	44	52
 CPOSG3G7	24	52
-CPOSA4A6	24	54
+CPOSA4A6	24	52
 CPOSB4B6	27	53
-CPOSC4C6	26	55
+CPOSC4C6	26	53
 CPOSD4D6	26	54
-CPOSE4E6	32	55
-CPOSF4F6	40	55
-CPOSG4G6	29	55
+CPOSE4E6	22	53
+CPOSF4F6	27	53
+CPOSG4G6	29	53
 CPOSA5	25	52
 CPOSB5	26	51
 CPOSC5	26	52