Better wrapping with Rust

Trying to hide most of the CXX nastiness behind the actual module
Move the CXX ffi stuff to its own module
Separate mgr and module mods
Modify main.rs to use the basic code we have done so far

src/module.rs

@@ -0,0 +1,20 @@
+use crate::cxx::ffi;
+use cxx::UniquePtr;
+
+pub struct Module {
+    module: UniquePtr<ffi::Module>,
+}
+
+impl Module {
+    pub fn new(module: UniquePtr<ffi::Module>) -> Self {
+        Self { module: module }
+    }
+
+    pub fn get_name(&self) -> String {
+        self.module.get_name()
+    }
+
+    pub fn strip_text(&mut self) -> String {
+        self.module.pin_mut().strip_text()
+    }
+}