Flatten API (#274)

Re-exports types from the toplevel instead of placing them in individual
modules (often which only contain one type).

This makes the API easier for users to navigate, while still retaining
the same module structure internally.

Additionally, this commit uses the `uuid` crate for modeling UUIDs.

src/config.rs

@@ -46,28 +46,28 @@ use std::{
 const CB_ADMIN_TIMESTAMP: usize = 0x04;
 const PROTECTED_FLAGS_1_PUK_NOBLOCK: u8 = 0x01;
 
-/// Config
+/// YubiKey configuration.
 #[derive(Copy, Clone, Debug)]
 pub struct Config {
     /// Protected data available
-    protected_data_available: bool,
+    pub protected_data_available: bool,
 
     /// PUK blocked
-    puk_blocked: bool,
+    pub puk_blocked: bool,
 
     /// No block on upgrade
-    puk_noblock_on_upgrade: bool,
+    pub puk_noblock_on_upgrade: bool,
 
     /// PIN last changed
-    pin_last_changed: Option<SystemTime>,
+    pub pin_last_changed: Option<SystemTime>,
 
     /// MGM type
-    mgm_type: MgmType,
+    pub mgm_type: MgmType,
 }
 
 impl Config {
-    /// Get YubiKey config
-    pub fn get(yubikey: &mut YubiKey) -> Result<Config> {
+    /// Get YubiKey config.
+    pub(crate) fn get(yubikey: &mut YubiKey) -> Result<Config> {
         let mut config = Config {
             protected_data_available: false,
             puk_blocked: false,
@@ -129,9 +129,7 @@ impl Config {
 
             if protected_data.get_item(TAG_PROTECTED_MGM).is_ok() {
                 if config.mgm_type != MgmType::Protected {
-                    error!(
-                        "conflicting types of mgm key administration configured: protected MGM exists"
-                    );
+                    error!("conflicting MGM key types: protected MGM exists");
                 }
 
                 // Always favor protected MGM