ENH: Allow numbers in username in URL regex.

Source/kwsys/SystemTools.cxx

@@ -78,7 +78,7 @@
 #endif
 
 #define VTK_URL_PROTOCOL_REGEX "([a-zA-Z0-9]*)://(.*)"
-#define VTK_URL_REGEX "([a-zA-Z0-9]*)://(([A-Za-z]+)(:([^:@]+))?@)?([^:@/]+)(:([0-9]+))?/(.+)?"
+#define VTK_URL_REGEX "([a-zA-Z0-9]*)://(([A-Za-z0-9]+)(:([^:@]+))?@)?([^:@/]+)(:([0-9]+))?/(.+)?"
 
 #ifdef _MSC_VER
 #include <sys/utime.h>