- Create separate libs for each architecture. OS X doesn't need this
(we just build a universal binary), but it will help Linux.
- Move the libuv build stuff into wren.mk where the actual dependency
on the lib is.
- Download libuv to deps/ instead of build/. That way "make clean"
doesn't blow it away.
- Don't redownload libuv unless needed.
- Add a script that downloads and compiles libuv.
- Hook that up to the Makefile so it pulls down libuv on build.
- Add a separate "vm" target that just builds the VM library and skips
libuv.
- Link to libuv when compiling the CLI.
- Update the XCode project to link to libuv too.
Linux and Windows support isn't done yet, but it should be pretty
straightforward to add to the Python script.
