Restructure module hierarchy by extracting meta and random from the core VM and CLI-specific modules into a new "aux" (auxiliary) directory. This introduces WREN_AUX_META and WREN_AUX_RANDOM configuration flags, updates include paths and build system to compile aux sources separately, removes random module registration from CLI modules.c, and adjusts the VM's module loading to implicitly import core into all modules regardless of name.
Migrate all Makefile references from script/wren.mk to util/wren.mk, update path for wren_to_c_string.py and libuv.py in build rules, and delete the entire project/msvc2013/ directory containing obsolete Visual Studio 2013 project files.
