Fixed severe bug in PSOCK_READTO (?)

Either I found and fixed a severe bug in PSOCK_READTO() or I misunderstood something completely. To me PSOCK_READTO() is supposed to return if either the supplied character was read or if the user supplied buffer is exhausted - sor far so good.

However if the latter occurs up to now PSOCK_READTO() was continuing to process characters already read from the network (aka present in the uIP buffer) in order to check if the supplied character was found there and adjust the return value accordingly. But this means that the character processed this way were lost forever for the caller as the next call to PSOCK_READTO() would continue to read past the characters processed this way.

Therefore I removed that character processing altogether. So now if the user supplied buffer is exhausted before the supplied character is found the next call to PSOCK_READTO() starts exactly where previous call left off.
Fixed severe bug in PSOCK_READTO (?)

Either I found and fixed a severe bug in PSOCK_READTO() or I misunderstood something completely. To me PSOCK_READTO() is supposed to return if either the supplied character was read or if the user supplied buffer is exhausted - sor far so good.

However if the latter occurs up to now PSOCK_READTO() was continuing to process characters already read from the network (aka present in the uIP buffer) in order to check if the supplied character was found there and adjust the return value accordingly. But this means that the character processed this way were lost forever for the caller as the next call to PSOCK_READTO() would continue to read past the characters processed this way.

Therefore I removed that character processing altogether. So now if the user supplied buffer is exhausted before the supplied character is found the next call to PSOCK_READTO() starts exactly where previous call left off.
Merge remote-tracking branch 'refs/remotes/origin/master'
Allow user to read the result of wget.

Several retro targets clear the screen after program termination so allow user to read the result.
Be consistent with tab chars in Makefiles.
Moved from last cc65 release (2.13.3) to recent cc65 snapshot (2.13.9).

Relevant cc65 changes...

General:
- The compiler generates "extended" dependency info (like gcc) so there's no need for postprocessing whatsoever :-)
- The linker is very pernickety regarding the ordering of cmdline options so a custom linker rule is necessary :-(

Apple2:
- The various memory usage scenarios aren't specified anymore via separate linker configs but via defines overriding default values in the builtin linker config.

Atari:
- The builtin linker config allows to override the start addr so there no more need for a custom linker config.
- The C library comes with POSIX directory access. So there's no more need for for a custom coding.

CBM:
- The C library comes with POSIX directory access. So there's no more need for for a custom coding.
The recent cc65 snapshot yields somewhat small programs so we can move back to the MTU size used before.
Reduced program size.

On the C128 the custom PFS code doesn't add functionality (as it does with IDE64 support on the C64) but is "only" smaller than the POSIX file i/o code in the C library. But the POSIX directory access code in the C library relies on the POSIX file i/o code anyway so there no point in additionally adding the PFS code to the FTP program.
Merge pull request #123 from oliverschmidt/master

Without anybody putting in a veto in the meantime it seems appropriate to merge now...