MXS-1775 Add mxs::[l|r]trimmed_copy(const std::string&)

Make it more convenient to get a left-trimmed, right-trimmed
or trimmed copy of a string.

include/maxscale/utils.hh

@@ -64,6 +64,49 @@ inline void trim(std::string &s)
     rtrim(s);
 }
 
+/**
+ * @brief Left-trimmed copy of a string.
+ *
+ * @param s  The string to the trimmed.
+ *
+ * @return A left-trimmed copy of the string.
+ */
+inline std::string ltrimmed_copy(const std::string& original)
+{
+    std::string s(original);
+    ltrim(s);
+    return s;
+}
+
+/**
+ * @brief Right-trimmed copy of a string.
+ *
+ * @param s  The string to the trimmed.
+ *
+ * @return A right-trimmed copy of the string.
+ */
+inline std::string rtrimmed_copy(const std::string& original)
+{
+    std::string s(original);
+    rtrim(s);
+    return s;
+}
+
+/**
+ * @brief Trimmed copy of a string.
+ *
+ * @param s  The string to the trimmed.
+ *
+ * @return A trimmed copy of the string.
+ */
+inline std::string trimmed_copy(const std::string& original)
+{
+    std::string s(original);
+    ltrim(s);
+    rtrim(s);
+    return s;
+}
+
 /**
  * @class CloserTraits utils.hh <maxscale/utils.hh>
  *