Remove some global 'using namespace's

persistent-data/data-structures/btree.h

@@ -380,7 +380,7 @@ namespace persistent_data {
 
 	private:
 		template <typename ValueTraits2, typename Search>
-		optional<typename ValueTraits2::value_type>
+		boost::optional<typename ValueTraits2::value_type>
 		lookup_raw(btree_detail::ro_spine &spine, block_address block, uint64_t key) const;
 
 		template <typename ValueTraits2>

persistent-data/data-structures/btree.tcc

@@ -24,9 +24,10 @@
 
 #include <iostream>
 
+// FIXME: remove
 using namespace base;
-using namespace btree_detail;
 using namespace persistent_data;
+using namespace btree_detail;
 using namespace std;
 
 //----------------------------------------------------------------