remove useless Logger to IStorm3D_Logger wrapper
remove signal handler code, it is useless
Make igios_backtrace demangle C++ function names
end backtrace before __libc_start_main

having a backtrace up to main is enough
Log missing files to a temporary log file for debugging

This commit is temporary and will be reverted soon
Do not log error message when opening some optional files
Remove coneAtiVertexShader

It is never used and the shader ource file for it does not exist.
Create a script to fix missing file warnings
No more missing file warning for Config/main.txt and empty save slots
fix missing scavenger_gore_partial.txt
fixed compilation with Clang
Add variadic log functions to Logger

This will allow removing strPrintf sometime