Tidy up declarations and files:

* Adjust formatting
* Fix inline namespace warning in main.cpp
* Fix streambuf op ambiguous variadic constructor
* Rename variables for clarity

test/main.cpp

@@ -41,6 +41,8 @@
 
 namespace beast {
 namespace detail {
+
+inline
 namespace unit_test {
 
 std::string

test/sig_wait.hpp

@@ -17,8 +17,8 @@
 */
 //==============================================================================
 
-#ifndef BEAST_TEST_SIG_WAIT_H_INCLUDED
-#define BEAST_TEST_SIG_WAIT_H_INCLUDED
+#ifndef BEAST_TEST_SIG_WAIT_HPP
+#define BEAST_TEST_SIG_WAIT_HPP
 
 #include <boost/asio.hpp>
 #include <condition_variable>