Changes from lib6502 version 0.2 to 0.6
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Log says:

0.5 -> 0.6:
	added getenvp
        added os version call getos
        changed cwd definition to let the app provide a buffer
        removed a/y length of data processed return value from fread/fwrite,
        added end-of-file comment to fread
        added "cwd" call
        added SIG_CHLD definition to signal
        added "yield" call

0.4 -> 0.5:
        moved file mode in fopen to xr
        Moved getenv/putenv from the Ideas section to an own subsection
        added directory entry definitions, added owner/group
            (this makes fsetattr equivalent to chmod and chown)
        remove no-block bit from freaddir, use fcntl(FC_RCHECK)
        E_FNAMLEN for name too long added to fopen
        absolute values for FC_* constants added
        fopen bits for exclusive etc added
        realloc added
        Trying to add more explicit values to not only have source but
                also binary compatibility someday
        getenv/putenv added to ideas section.

0.3 -> 0.4:
        completely moved to bi-directional file-nos
        added more comments on flock
        introduced fcntl(FC_RCHECK) and fcntl(FC_WCHECK)
        put a note for the directory into the fopen() description

0.2 -> 0.3:
        added fseek
        added stddup
        changed forknexec to forkto
        added forkthread
        added how to get list of file devices
        added how a program is started (main, a/y=pars)
        added o65 impementation notes.
        added dup call and notes about read-write file-nrs
        added kill