xo-unit: kitchen-sink doc + build improvements + 1 bug fix

example/ex8/CMakeLists.txt

@@ -0,0 +1,12 @@
+# xo-unit/example/ex8/CMakeLists.txt
+
+set(SELF_EXE xo_unit_ex8)
+set(SELF_SRCS ex8.cpp)
+
+if (XO_ENABLE_EXAMPLES)
+    xo_add_executable(${SELF_EXE} ${SELF_SRCS})
+    xo_self_headeronly_dependency(${SELF_EXE} xo_unit)
+    xo_dependency(${SELF_EXE} xo_flatstring)
+endif()
+
+# end CMakeLists.txt

example/ex8/ex8.cpp

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+/** @file ex8.cpp **/
+
+#include "xo/unit/xquantity.hpp"
+#include "xo/unit/xquantity_iostream.hpp"
+#include <iostream>
+
+int
+main () {
+    using namespace xo::qty;
+    namespace u = xo::qty::u;
+    //namespace q = xo::qty::qty;
+    using namespace std;
+
+    xquantity qty1(7, u::foot);
+    xquantity qty2(6.0, u::inch);
+    xquantity qty3 = qty1 + qty2;
+
+    cerr << "qty1: " << qty1 << endl;
+    cerr << "qty2: " << qty2 << endl;
+    cerr << "qty3: " << qty3 << endl;
+
+    /* rescale to mm */
+    xquantity res = qty3.rescale(xo::qty::nu::millimeter);
+
+    /* 2286mm */
+    cerr << "res: " << res << endl;
+}
+
+/** end ex8.cpp */