Compile Error for Arduino Zero

[qbiq]

If I try to compile a sketch using i nthe Arduino IDE using the SAMD architecture (Arduino Zero), I get the following error:

`C:\Users\quino\Documents\Arduino\libraries\WiFiEsp\src/utility/RingBuffer.h:23:7: error: redefinition of 'class RingBuffer'``

Removing the lines 30,31 & 32 solves the compilation errors:
`//#include "utility/EspDrv.h"

//#include "utility/RingBuffer.h"

//#include "utility/debug.h"`

But then I have a new issue:
'WL_IDLE_STATUS' was not declared in this scope

[pantata]

My fix for Arduino M0:

• rename files and class RingBuffer -> RingBuffer2
• EspDrv.cpp: add macro

#if defined(__SAMD21G18A__)
#define vsnprintf_P  vsnprintf
#endif

• and I add TCP_ prefix to enum wl_tcp_state (conflict with Keypad lib)

[Urs-O]

This Bug is also been adressed by Pull Request #27
@bportaluri Would you be so kind to merge that Pullrequest? That would be really nice.