lib/progess.c file, and is now used with the new progress callback function

removed the "mode" concept
moved all #-stuff to the client

I also use typecasted size_t now for systems with unsigned such ones

now returns -1 from FormReader() when the last form data has been read!

files depend on that as well. It turned out Borland has no unistd.h file
either, only mingw32 seems to use that.

changed ftp-ascii to use-ascii and its explanation was fixed

added the progress function callback and data pointer
added the callback typedefs