Backport: Trunk r8561 + r8565; PVS-Studio fixes: Resolve some warnings about use of pointers before checking for a null pointer && partial revert of 8561: vm_malloc should never return null, so the Assert is necessary, and will immediately flag the error as it happens instead of leaving a mine to be triggered later
mod - /branches/fs2_open_3_6_14/code/nebula/neb.cpp
