DATAMATRIX: new algorithm for (near-)minimal encoding, props Alex Geller

Add FAST_MODE input_mode flag and --fast CLI/Tcl option that selects older
  faster ISO algorithm (may be used by other symbologies in the future)
  and "Fast Encoding" checkbox to Data Matrix GUI
GUI: adds Zint version numbers to DATAMATRIX sizes.

backend_qt/backend_vc8.pro

@@ -26,6 +26,7 @@ HEADERS +=  ../backend/aztec.h \
             ../backend/common.h \
             ../backend/composite.h \
             ../backend/dmatrix.h \
+            ../backend/dmatrix_trace.h \
             ../backend/eci.h \
             ../backend/emf.h \
             ../backend/font.h \