Set a WP transient expiration one year in the future instead of makin…

…g it indefinite.

* With the default options-table based transient cache, indefinitely stored transients are autoloaded.
* By setting an expiration date in the far-future, it is *effectively* indefinite, but we get the benefit of no autoloading of what might be a very large options row.

props to @YousefED for bringing the issue to my attention. fixes #10

tlc-transients.php

@@ -94,9 +94,9 @@ public function fetch_and_cache() {
 
 		public function set( $data ) {
 			// We set the timeout as part of the transient data.
-			// The actual transient has no TTL. This allows for soft expiration.
+			// The actual transient has a far-future TTL. This allows for soft expiration.
 			$expiration = ( $this->expiration > 0 ) ? time() + $this->expiration : 0;
-			set_transient( 'tlc__' . $this->key, array( $expiration, $data ) );
+			set_transient( 'tlc__' . $this->key, array( $expiration, $data ), 31536000 ); // 60*60*24*365 ~= one year
 			return $this;
 		}