https://forum.pjrc.com/threads/32834-SPI-disable-not-working-correctly-with-setMOSI-setMISO-setSCK

https://forum.pjrc.com/threads/33072-IntervalTimer-h-bug

Add MOUSE_BACK, MOUSE_FORWARD

Add MOUSE_BACK, MOUSE_FORWARD

https://forum.pjrc.com/threads/32999-using-IntervalTimer-with-SPI-usingInterrupt%28%29

Add INPUT_PULLDOWN and OUTPUT_OPENDRAIN options for pinMode()

fixes #109

Sometimes the PC or Mac drivers are not actually ready to begin receiving data immediately after they cause DTR or RTS to assert.  This delay allows the PC to become ready before we tell sketches the Serial device is true (ready).

Those that specify a NO_ARDUINO environment variable before using
the teensy3/Makefile, will be completely Arduino independent. Note
however that if ARDUINOPATH is set, the NO_ARDUINO behaviour will
be overridden. With NO_ARDUINO set and ARDUINOPATH unset, the
cross-compiler tool path (COMPILERPATH) will be set to /usr/bin.
Setting the COMPILERPATH environment variable before using the
teensy3/Makefile, will override the default.

Some path-variables in the teens3/Makefile passes though abspath
every time before they get used. Do this only once, when they get
set. This makes things more readable and less error-prone.