MiniVMac.cc always creates a 4.7MiB disk image which may be too small

[ryandesign]

MiniVMac.cc always creates a disk image of size 5000*1024 bytes, then copies the operating system and the autoquit/autquit7 program and the user's app onto it. The disk image may be too small to contain all these things, or it may be larger than needed. Could it instead create a disk image that is the right size, taking into account the size of everything that needs to be copied to it, plus a little extra to build the desktop file and in case the app needs to write some data of its own?