Add printf to source files

[blhough]

printf doesn't work by default for some reason. You must modify the source code included in the teensy library.

follow instructions here:
http://playground.arduino.cc/Main/Printf#sourceblock1

Summary:
In directory: {installdir)/hardware/teensy/cores/teensy3/

comment out lines 87-107 in Print.cpp

comment out lines 98 and 99 in Print.h
paste this code below

#include <stdarg.h>
#define PRINTF_BUF 200 // define the tmp buffer size (change if desired)
int printf(const char *format, ...)
{
	char buf[PRINTF_BUF];
	va_list ap;
	va_start(ap, format);
	int  n = vsnprintf(buf, sizeof(buf), format, ap);
	for (char *p = &buf[0]; *p; p++) // emulate cooked mode for newlines
	{
		if (*p == '\n')
			write('\r');
		write(*p);
	}
	va_end(ap);
	return n;
}
#ifdef F // check to see if F() macro is available
int printf(const __FlashStringHelper *format, ...)
{
	char buf[PRINTF_BUF];
	va_list ap;
	va_start(ap, format);
#ifdef __AVR__k
	int n = vsnprintf_P(buf, sizeof(buf), (const char *)format, ap); // progmem for AVR
#else
	int n = vsnprintf(buf, sizeof(buf), (const char *)format, ap); // for the rest of the world
#endif
	for (char *p = &buf[0]; *p; p++) // emulate cooked mode for newlines
	{
		if (*p == '\n')
			write('\r');
		write(*p);
	}
	va_end(ap);
	return n;
}
#endif

I don't know an easy way to make this part of our project code