Additional PR for SERIALX_DISABLE follows

Fix fcvtf warning in newer versions of newlib

Fix compilation error with recent newlib/gcc versions because of random()

Fix compilation warnings related to kinetis_hsrun_enable() for older teensies

fixed toolspath

The spaces after TOOLSPATH will append to the variable value. Merged the on Linux comment with previous comment to fix.

EEPROM write on T_3.6 under HSRUN - Drop and Raise

Fix issue #181. Improved pin interrupt dispatch performance.

T3.5/3.6 - SPI has additional Miso/Mosi/SCK pins

Earlier I had pin 20 as the default SCK1, but card shows that pin 32 is
the default pin

nbytes transfer count when minor loop enabled is 10 bits not 5

close hole for race condition

Has to add core_pins.h to get delayMicroseconds()
made empty while()'s on HSRUN state change have a measurable 2us wait
each iteration
added explicit 100us delay leaving HSRUN to allow internal V to
satbilize, seems CPU does this already as 10-50 us made no change, and
100 is not measurable on larger writes.
since eeprom_initialize() blindly restores interrupts amd can run under
HSRUN, moved hsrun_off()

EEPROM write on T_3.6 under HSRUN - Drop and Raise

Drop HSRUN across Ser# read with interrupts off

https://forum.pjrc.com/threads/34808-K66-Beta-Test?p=116690&viewfull=1#post116690

Results in valid serial # presented to USB host when T_3.6 is in HSRUN mode.

Fix PWM and Analog Pin counts om T3.5 and T3.6

Added in the additional SPI pins
MISO 39
MOSI 28
SCK 27

Tested with my ILI9341_t3n (SPIN) version.  Will also
Add to ILI9341_t3.

Recent additions did not update these counts.

Seperated T3.5 from T3.6 as PWM and Analog counts are different

T35 use sdcard pins

Add A23 and A24 for T3.5 and T3.6 board

Fix spi0 dma for t3 5

Fix Serial6 for Teensy 3.5

Needed to add new Define for clock gate

Plus defines to use the new clock gate, plus correct case name for the
serial6 isr to match what is in system isr table

I added pins  49 and 50 as analog pins A23 and A24.  I still left in the
special casing for pins 44 and 45 being used for Temp and analog
reference

With the new beta boards, for those users who don't need an SDCard for
their project, it would be great to allow them to use the 6 IO pins
associated with the SDCARD for other purposes.  This would probably
require a cheap adapter, but these are nice signals to be able to be
used.  They include:

SPI1: SCK, MISO, MOSI, CS0-2
Serail2: TX/RX
Serial4: TX/RX
I2C1: SCL/SDA

This change adds support for GPIO, SPI, Serial2 and Serial4