wee warning cleanup + build doc updates (#156)

* warning cleanup
* test compilation
* clarification on architecture in build doc, path export statement fix

pool/src/graph.rs

@@ -20,7 +20,6 @@ use std::collections::HashMap;
 use secp::pedersen::Commitment;
 
 use time;
-use rand;
 
 use std::fmt;
 
@@ -250,6 +249,7 @@ mod tests {
 	use super::*;
 	use secp;
 	use keychain::Keychain;
+	use rand;
 
 	#[test]
 	fn test_add_entry() {

pool/src/pool.rs

@@ -21,8 +21,6 @@ use core::core::transaction;
 use core::core::block;
 use core::core::hash;
 use core::global;
-use core::global::{MiningParameterMode, MINING_PARAMETER_MODE};
-use core::consensus;
 
 use secp;
 use secp::pedersen::Commitment;
@@ -131,7 +129,7 @@ where
 	) -> Result<(), PoolError> {
 		// Making sure the transaction is valid before anything else.
 		let secp = secp::Secp256k1::with_caps(secp::ContextFlag::Commit);
-		tx.validate(&secp).map_err(|e| PoolError::Invalid)?;
+		tx.validate(&secp).map_err(|_e| PoolError::Invalid)?;
 
 		// The first check involves ensuring that an identical transaction is
 		// not already in the pool's transaction set.
@@ -565,6 +563,7 @@ mod tests {
 	use keychain::Keychain;
 	use std::sync::{Arc, RwLock};
 	use blake2;
+	use core::global::MiningParameterMode;
 
 	macro_rules! expect_output_parent {
 		($pool:expr, $expected:pat, $( $output:expr ),+ ) => {