`process_boss()` will no longer automatically start the next attack
after the current one ends. Instead, it will set the current attack to
NULL and signal the next attack's `initiated` event. The attack starts
when the event handler calls the `BEGIN_BOSS_ATTACK()` macro. This
allows the attack task to arbitrarily delay the attack phase activation.
Note that `BEGIN_BOSS_ATTACK()` still waits for the `started` event,
which is signaled after `BEGIN_BOSS_ATTACK()` plus an inherent attack
delay (ATTACK_START_DELAY etc.) For regular attacks that don't wish to
delay `BEGIN_BOSS_ATTACK()`, this change is effectively invisible.
* WIP portrait faces
* character expressions for dialogue in first 3 stages (wip)
* dialog: simplified face system, new faces, script revisions (wip)
* fix wrong face name in reimu script
* cirno angry face; elly beaten variant
* render_character_portrait(): fix garbage bg and filter-bleeding
* workaround for incorrect face blending on dialog fade
* render_character_portrait(): fix bogus debug labels
* Replace sprite offsets with the more powerful paddings
* new faces for youmu, wriggle, kurumi; dialogue updates
* fix release build
* Update portraits; add Iku faces and Elly shouting face
* Add Reimu sigh face and Marisa sweat_smile face
* Add Kurumi dissatisfied face
* update Hina