Squashed bugs found by @mikekaganski; See #483

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>

src/CoolPropTools.cpp

@@ -30,7 +30,7 @@ std::string format(const char* fmt, ...)
     va_start(vl,fmt);
     int nsize = vsnprintf(buffer,size,fmt,vl);
     if(size<=nsize){//fail delete buffer and try again
-        delete buffer; buffer = 0;
+        delete[] buffer; buffer = 0;
         buffer = new char[nsize+1];//+1 for /0
         nsize = vsnprintf(buffer,size,fmt,vl);
     }