sendto and recvfrom take a char* and not void* on Win32.
Add realloc casts
Reorder copy_file to calm Visual Studio warning

Visual Studio code flow analysis fails to recognize that buf is always
assigned at least once.  Reorder the logic to encourage it to recognize
this.
Fix memory leak on realloc failure in PHYSFSX_*
Use CALLOC for hashtable_init
Remove unused ksegsize.c
Rename replacement new for C++ compatibility
Move similar/main/net_udp.c -> similar/main/net_udp.cpp
Move similar/main/newdemo.c -> similar/main/newdemo.cpp
Move similar/main/newmenu.c -> similar/main/newmenu.cpp
Move similar/main/object.c -> similar/main/object.cpp
Move similar/main/paging.c -> similar/main/paging.cpp
Move similar/main/physics.c -> similar/main/physics.cpp
Move similar/main/player.c -> similar/main/player.cpp
Move similar/main/playsave.c -> similar/main/playsave.cpp
Move similar/main/polyobj.c -> similar/main/polyobj.cpp
Move similar/main/powerup.c -> similar/main/powerup.cpp
Move similar/main/render.c -> similar/main/render.cpp
Move similar/main/robot.c -> similar/main/robot.cpp
Move similar/main/scores.c -> similar/main/scores.cpp