Add demangling for f16 and f128

`k` was selected for `f16` and `q` for `f128`. These are different from LLVM's
defaults.

Author: tgross35

src/v0.rs

@@ -385,8 +385,10 @@ fn basic_type(tag: u8) -> Option<&'static str> {
         b'y' => "u64",
         b'o' => "u128",
         b'j' => "usize",
+        b'k' => "f16",
         b'f' => "f32",
         b'd' => "f64",
+        b'q' => "f128",
         b'z' => "!",
         b'p' => "_",
         b'v' => "...",