Compile with '-std=c++11 -fvisibility=hidden -fno-rtti'.

-std=c++11: compile in c++11 mode
-fvisibility=hidden: only export the symbols we explicitly mark. Helps
 optimization and reduces binary size
-fno-rtti: disable RTTI
Return an std::streambuf instead of std::{i,o}stream
Add EVFS::RW_VFS interface