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

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.

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

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

https://forum.pjrc.com/threads/35688-Something-wrong-with-Adding-a-String-to-itself!?p=111109#post111109

The T-LC and the new beta boards T3.6 and soon T3.5 hardware uarts have
ability to turn on 2 stop bits.  So enabled on these boards.

Was using UART2, should be UART3

On T3.2 if you do something like:
Serial2.setTX(31);
Serial2.setRX(26);
Serial2.begin(.9600);
...
Serial2.end();

It will on the end call will always reconfigure pins 9 and 10 to be
digital pins MUX = 1

fixes #159

Make update of these flags be hopefully interrupt safe

This is a WIP,  But I have now been able to create Serial6 on T3.4 beta,
and so far have tested Send/Receive basic stuff at 115200 and have tried
at several CPU speeds in MHZ (192, 216, 180, 120, 96)

These two functions were checking (SIM_SCGC4 & SIM_SCGC4_UART2)
and should be testing (SIM_SCGC4 & SIM_SCGC4_UART1)

fixes #145

PulseIn may fail on LC as it is using *reg to test the value for on or
off, but on LC register is a bitmask associated with several IO pins.
So split off for LC to use the MASK value for the pin to test high and
low.

Warning did not update timings for this,  which may be necessary as adds
an & in the loop.  However when I tried TLC for 5000us timeout, it timed
out with 5138us, if I decremented the PULSEIN_LOOPS_PER_USEC by one,
then it timed out at 4398... This was at 49mhz.