New unit_test framework:

* Header-only!
* No external dependencies or other beast modules
* Compilation options allow for:
  - Stand-alone application to run a single test suite
  - Stand-alone application to run a set of test suites
  - Global suite of tests inline with the host application
  - Disable test suite generation completely
* Existing tests reworked to use the new classes

src/ripple_data/protocol/STAmountRound.cpp

@@ -17,6 +17,8 @@
 */
 //==============================================================================
 
+namespace ripple {
+
 void STAmount::canonicalizeRound (bool isNative, beast::uint64& value, int& offset, bool roundUp)
 {
     if (!roundUp) // canonicalize already rounds down
@@ -311,3 +313,4 @@ STAmount STAmount::divRound (const STAmount& num, const STAmount& den,
     return STAmount (uCurrencyID, uIssuerID, amount, offset, resultNegative);
 }
 
+} // ripple