Implement From instead of Into

Implementing `From` gives us an implementation of `Into` for free so is
therefore superior.

Found by Clippy.

src/network/constants.rs

@@ -238,9 +238,9 @@ impl From<u64> for ServiceFlags {
     }
 }
 
-impl Into<u64> for ServiceFlags {
-    fn into(self) -> u64 {
-        self.0
+impl From<ServiceFlags> for u64 {
+    fn from(flags: ServiceFlags) -> Self {
+        flags.0
     }
 }
 

src/util/bip32.rs

@@ -283,9 +283,9 @@ impl From<Vec<ChildNumber>> for DerivationPath {
     }
 }
 
-impl Into<Vec<ChildNumber>> for DerivationPath {
-    fn into(self) -> Vec<ChildNumber> {
-        self.0
+impl From<DerivationPath> for Vec<ChildNumber> {
+    fn from(path: DerivationPath) -> Self {
+        path.0
     }
 }