If you allocate a vector on the stack and default initialise
it (i.e. {0}), then by default "is_inlined" = 0. This is bad, as
technically speaking we should expect the vector to attempt to use
it's small inline buffer for vector operations before going onto the
heap - this will mess up our functions. So here I adjust the name to
make default stack based allocation a bit easier.
Since most use cases require indexing the data directly, and the macro
implies you're retrieving data from it, may as well take the index.
If you wanted a pointer to that data, &VEC_GET(vec, index, type) works
just fine.
Easier to iterate through, O(1) amortized registering just like the
Linked List.
VEC_SIZE just makes it easier to iterate through a vector of specially
typed elements.
