Add DISCO_F303VC

http://www.st.com/en/evaluation-tools/stm32f3discovery.html

Author: jeromecoutant

mbed_lstools/platform_database.py

@@ -103,6 +103,7 @@
     u'0743': u'DISCO_F413ZH',
     u'0744': u'NUCLEO_F410RB',
     u'0745': u'NUCLEO_F303RE',
+    u'0746': u'DISCO_F303VC',
     u'0747': u'NUCLEO_F303ZE',
     u'0750': u'NUCLEO_F091RC',
     u'0755': u'NUCLEO_F070RB',