Use C++14 on 32 bit Teensy boards

Add pure code choices in Tools > Optimization
Fix Wire lib with fastest optimize and >120 MHz CPU speed
Wire emulate AVR twi_writeTo - for Adafruit compatibility
Wire1 support pins on Teensy 3.5 & 3.6 SD socket (if not using SD card)
Fix install problem on Arduino 1.0.6
Fix analogReadAveraging with ADC1
Allow more memory for audio library on Teensy 3.5 & 3.6
Fix audio library delay effect on Teensy 3.5 & 3.6
Audio I2S uses 64 bit frame, improve compatibility with I2S mics
Fix OctoWS2811 seldom-used color conversion options
USBHost_t36 improved handling of error & pipe stall 

Support for Arduino 1.8.4
fix for disable of SD on Teensy 3.5 & 3.6 (Frank)
SPI.transfer(readbuf, writebuf, size) (KurtE)
Added TeensyThreads library (Fernando Trias)
Fixed Adafruit_CC3000 on Teensy 3.x
Audio envelope graceful handling of noteOn while gain > 0
Improved FreqMeasureMulti countToNanoseconds
[Experimental] EventResponder
[Experimental] MillisTimer
[Experimental] SPI async using DMA & EventResponder (KurtE)

Remove 2.5 second wait in Serial.begin
USBHost_t36 mouser driver (wwatson)
Update Adafruit_CC3000, AccelStepper, Adafruit_GFX, Adafruit_SSD1306, FastLED, IRremote, Keypad, MFRC522, SoftPWM, SPIFlash 

Symbol table and disassembly listing are placed in temp build folder
Fix audio memory usage stats when more than 255 blocks allocated
Fix USB audio transmit with null data
Audio library support for external delay with CY15B104 (FrankB)