Currently, unless exponential growth is enabled, BADOSs expand as follows:
new_length = remaining_length + new bytes required + 32

If we have a 1024 buffer with pos=4 and want to add 1024 bytes, then we expand the buffer to 1020 + 1024 + 32 = 2076 bytes which is wasted space.

I'm changing this to
new_length = pos + new bytes required + 32. In the above example, we'd expand the buffer to 1060 bytes.

If we really wanted bigger expansion, exponential growth should be enabled.