(svn r13708) [0.6] -Backport from trunk:
- Fix: Possible buffer overflow in string truncation code (r13700)
- Fix: Handle SETX(Y) properly when truncating a string instead of ignoring it and returning a too long string (r13699)
- Fix: In some cases the (sound) mixer could overflow causing artefacts in the sound [FS#2120] (r13695)
- Fix: Do not rely on .tar files always ending with a block of zeros (r13693)
- Fix: Make sure a command is ran in the context of autoreplace or not (r13691)
