logic: Trim lines and remove empty ones when checking license key

src/lib/utility/utilityString.cpp

@@ -168,4 +168,11 @@ namespace utility
 
 		return str;
 	}
+
+	std::string trim(const std::string &str)
+	{
+		auto wsfront = std::find_if_not(str.begin(), str.end(), [](int c){ return std::isspace(c); });
+		auto wsback = std::find_if_not(str.rbegin(), str.rend(), [](int c){ return std::isspace(c); }).base();
+		return (wsback <= wsfront ? std::string() : std::string(wsfront, wsback));
+	}
 }