k
some svdemo cleanups.  fix bug where we wrote the wrong initial sequence
number causing start of demos to be wonky.
make sure we don't delta against a frame not written to the demo
bump up size of demoname to avoid truncation
use the same time format as CL_DemoFilename for default and autorecord demos
move the recursive rmdir to files.cpp, separate logic from FS_HomeRemove
clean up imports so only files.cpp needs the extra headers