Misc Cleanup 2 (#1007)

* Cleanup `UNK_TYPE`, `UNK_PTR` usage

* Add some missing empty lines after declarations

* Remove some legacy comments from non-matching times

* Fix some grammar (mostly "it's"/"its")

* Use proper names for two symbols after ZAPD bugfix

* Cleanup `place_title_cards.xml`

* Use `NULL` to check against `D_8012D260` pointer

* Parentheses around some macro arguments

* wip proofread headers up to z64animation.h

src/code/code_800FCE80.c

@@ -6,6 +6,7 @@ s32 gUseAtanContFrac;
 f32 Math_FTanF(f32 x) {
     f32 sin = sinf(x);
     f32 cos = cosf(x);
+
     return sin / cos;
 }