Delete get_env, which confused me a lot.

Get raw environment variables directly from main().
Add code to split on '=' in cgi_environment_vars and only pick
the ones that are interesting, just as before.

src/tawashi_implem/cgi_env.cpp

@@ -81,8 +81,8 @@ namespace cgi {
 		}
 	} //unnamed namespace
 
-	Env::Env() :
-		m_cgi_env(cgi_environment_vars())
+	Env::Env(const char* const* parEnvList) :
+		m_cgi_env(cgi_environment_vars(parEnvList))
 	{
 	}