Add basic var support to the org-src blocks.

[bergmannf]

This will just wrap the variables into &str (or &[&str]) constants.

It will also not care about the types of the passed variables, except if they are lists - all other type information doesn't matter - everything will be a &str in the end.

Example:

#+name: mytbl
| A | B |
|---+---|
| a | b |
| c | d |
|   | g |
| e | f |

#+begin_src rust :var A=mytbl :var B='("b" "c") :var C="c"
println!("{:?}", A);
println!("{:?}", B);
println!("{:?}", C);
#+end_src

#+RESULTS:
: [["a", "b"], ["c", "d"], ["", "g"], ["e", "f"]]
: ["b", "c"]
: "c"

[CeleritasCelery]

This seems like a big enough addition that it would be worth adding some tests here.

[bergmannf]

Ah thanks for the pointer - I only checked where to add it and didn't even check for tests, so 100% agreed on adding some tests! Let me take a look at that.

[CeleritasCelery]

Thanks!