Add a lot of new stuff to the compile mod

* compile::sym is now compile::name
* add basic block structure
* add visitor pattern
* some other minor things (e.g. syn::ast::prelude)

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

src/compile/error.rs

@@ -0,0 +1,9 @@
+use snafu::Snafu;
+
+#[derive(Debug, Snafu)]
+pub enum Error {
+    //#[snafu(display("illegal attr key"))]
+
+}
+
+pub type Result<T, E = Error> = std::result::Result<T, E>;