Songs aegis behavior updated. Bonus correction

- Fixed bug 8412 http://hercules.ws/board/tracker/issue-8412-songs/ Now songs auto-refreshes every 3 seconds.
- Musical Lesson bonus rounded down for BA_ASSASSINCROSS.
Fixes song affecting caster without link
In linux enable thin-stream mode.

It should reduce latency in some cases.

See more info here: https://www.kernel.org/doc/Documentation/networking/tcp-thin.txt
Merge pull request #421 from csnv/songredo

Songs aegis behavior updated. Bonus correction
Merge pull request #422 from 4144/thinsock

In linux enable thin-stream mode.

Note: If anyone has a reason to disable this, please tell us, and we'll turn it into a compile-time option.
Fix possible memory overflows and underflows.
Add some missing null pointer checks after automatic checks.
Remove useless checks.
fix typo in inter.c in initerface initialisation.
Fix wrong useless cycle added in commit c47d8e4b8f9d63ab6b4e7e286e91cd50a5bdd151.
Fix checking result from function TryEnterCriticalSection.
fix wrong check.
add comment about possible error.
Improve performance a bit by removing strlen(str) > 0.