Minor fixes (#6)

* cmake: require c++14

* correctly clip samples

by using numeric_limits rather than C macros

* oops, implicit type conversion of template causes overflow

* store default sample rate in global constexpr var

driver/amuserender.cpp

@@ -99,7 +99,7 @@ int main(int argc, const boo::SystemChar** argv)
 
     std::vector<boo::SystemString> m_args;
     m_args.reserve(argc);
-    double rate = 32000.0;
+    double rate = NativeSampleRate;
     for (int i = 1; i < argc; ++i)
     {
 #if _WIN32