Print libflo's version on "--version"

This lets me verify that users have the lastest libflo, which may be
important when trying to fix bugs.
Merge remote-tracking branch 'origin/print_libflo_version'

This depended on the latest libflo, which is why I was waiting to
merge it in.

Conflicts:
	src/main-c++.c++
Fix a missing "]" in generated code

I should really be using libcodegen to generate my C++ sources, but
I'm lazy and don't want to port it...
Make flo-llvm call the correct flo-llvm-c++

I shouldn't be calling the "flo-llvm-c++" that's in my PATH but
instead the one that's directly next to how "flo-llvm" was called.