[collision] implement most of background collision, spawn target! (#1076)

* fill collide cache with bounding box working

* yprobe fully working for background at least

* target

* final cleanup, add a bit more foreground mesh stuff that is untested

* warnings, merge issues

* tests

* revert debug changes, format'

* rendering perf

game/kernel/klink.cpp

@@ -889,6 +889,7 @@ void ultimate_memcpy(void* dst, void* src, uint32_t size) {
       auto sym = find_symbol_from_c("ultimate-memcpy");
       if (sym->value == 0) {
         memmove(dst, src, size);
+        return;
       }
       gfunc_774.offset = sym->value;
     }