Add support for (configurable) multiline hotbar
Improved screensize handling
Add userdefined gui scale by BlockMen

This reverts commit 5b518ed2.

This caused duplicate tracebacks and tracebacks when unwanted.
It also ignored the level argument to error() and didn't pass the message (or level) to debug.traceback().
Use xpcall() or lua_pcall()'s errorhandler argument instead.

This reverts commits a2003b0d and 54ffe2e5.

These weren't correct.  Add a black magic warning instead.

Thats updated #795

Add log entry for peer timeout

add c++11 atomic support (optional)