Socket fix

[gerdr]

Return undefined from IO::Socket::INET.get on reaching end-of-stream and actually loop in IO::Socket::INET.lines

Also makes sure that overlong lines won't be split.

[gerdr]

This improves upon the current situation, but does not fix all issues. In particular:

• overlong lines will still be split even if no separator has been reached yet fixed by gerdr@dfe1eb7
• when iterating gather/take, there's apparently some pre-fetching happening, which does not work with blocking calls
• there's a Parrot issue which prevents the last separator to be detected until the stream has been closed fixed by [BUGFIX] Fix issue #942 parrot/parrot#943

[gerdr]

Depending on how my question on parrot-dev turns out, the second commmit might be replaced by a parrot-side change.

[gerdr]

Having taken another look at the code, the second commit does indeed not handle the case of split multi-character separators correctly.

A proper fix will probably end up buffering partial lines between calls to get(). I'm waiting for some answer on parrot-dev before tackling that.

[gerdr]

now obsolete - see #115