[Reverse-engineering] [th04/th05] Remaining generic boss variables

… yeah, I don't really like these ambiguous "mode" and "mode change"
variable names either, but what's the alternative? Something something
"sub-phase", to distinguish them from regular phases? Feels way too
early to decide on something more specific. And pretty much nothing I
could come up with right now would have made their inconsistent use any
clearer.
But I need to decide on *something* before moving on, so… eh, let's
just go with what uth05win chose.

Also, yeah, dealing with those 0xFE and 0xFD boss_phase constants some
other time 😛

Also, today in "Weird TASM crashes": Trailing commas at the end of
`public` lines…

Completes P0028, funded by zorg.

th04/boss/vars[bss].asm

@@ -0,0 +1,15 @@
+public _boss_pos, _boss_hp, _boss_sprite, _boss_phase, _boss_phase_frame
+public _boss_damage_this_frame, _boss_mode, _boss_angle, _boss_mode_change
+public _boss_phase_end_hp
+
+_boss_pos	motion_t <?>
+_boss_hp	dw ?
+_boss_sprite	db ?
+_boss_phase	db ?
+_boss_phase_frame	dw ?
+_boss_damage_this_frame	db ?
+_boss_mode	db ?
+; Used for both movement and bullet angles.
+_boss_angle	db ?
+_boss_mode_change	db ?
+_boss_phase_end_hp	dw ?

th05/boss/vars2[bss].asm

@@ -2,8 +2,12 @@
 ; of the Stage 4 boss fight, for Shinki's leave animation at the beginning of
 ; the Stage 5 boss fight, and, weirdly enough, for the knife launch position
 ; in Phase 8 of the same fight.
-public _boss2_pos, _boss2_hp, _boss2_sprite
-public  _yuki_pos,  _yuki_hp,  _yuki_sprite
+public _boss2_pos, _boss2_hp, _boss2_sprite, _boss2_phase, _boss2_phase_frame
+public  _yuki_pos,  _yuki_hp,  _yuki_sprite,  _yuki_phase,  _yuki_phase_frame
+public _boss2_damage_this_frame, _boss2_mode, _boss2_angle, _boss2_mode_change
+public  _yuki_damage_this_frame,  _yuki_mode,  _yuki_angle,  _yuki_mode_change
+public _boss2_phase_end_hp
+public  _yuki_phase_end_hp
 
 label _yuki_pos motion_t
 _boss2_pos	motion_t <?>
@@ -14,5 +18,23 @@ _boss2_hp 	dw ?
 label _yuki_sprite byte
 _boss2_sprite	db ?
 
-	db ?
-_boss2_unused	dw ?
+label _yuki_phase byte
+_boss2_phase	db ?
+
+label _yuki_phase_frame word
+_boss2_phase_frame	dw ?
+
+label _yuki_damage_this_frame byte
+_boss2_damage_this_frame 	db ?
+
+label _yuki_mode byte
+_boss2_mode	db ?
+
+label _yuki_angle byte
+_boss2_angle	db ?
+
+label _yuki_mode_change byte
+_boss2_mode_change	db ?
+
+label _yuki_phase_end_hp word
+_boss2_phase_end_hp	dw ?