A repeated pattern in Magicka is to append to dynamically
sized arrays via malloc()/realloc(). Introduce the notion
of a "pointer vector": that is, a growable vector of
pointers, that can be reused to implement that logic more
safely and efficiently (this implementation uses power-of-two
growing).
Many malloc()/realloc() calls were not checked; these
assert() that the return value from realloc() is not NULL.
Add a method to consume the pointer vector: that is, realloc()
it to the current length and return the underlying pointers.
Make the `fmt` argument to dolog() const.
Include <sys/wait.h> in bluewave.c to squash a warning.
Signed-off-by: Dan Cross <patchdev@fat-dragon.org>
