[NUCLEO_F072RB] Remove call to systick
[NUCLEO_F091RC] Remove call to systick
Fix a bug that I2C driver can not transfer of 1Byte/2Byte.

I2C driver was not considered about 1Byte/2Byte transfer.
Add 1Byte/2Byte transfer processing in I2C driver.
Fix a bug that initialize setting of SPI clock value is not correct.

Modify the value as below.
　uint16_t mask = 0x000c0; ->
　uint16_t mask = 0x000c;
Fix some bugs that IRQ Edge Interrupt will not operation normal.

The bugs of IRQ Edge Interrupt as below.
- Not call a function that was registered in rise, always call a function that was registered in the fall.
- If there are multiple interrupt sources, there is a possibility that end the wrong interrupt processing.
Add definition of User button(SW0 and SW1)

Add definition of User button for users.
Fix a bug that usticker wait interval is not constant.

When read the timer value, it have a potential to read abnormal value.
Because we used 16bit + 16bit cascade timer and read timer count separately.
Changed usticker timer from 16bit + 16bit cascade timer to 32bit timer to fix the bug.
Change I2C driver transfer sequence

Change I2C driver transfer sequence to go according to H/W manual.
Changed contents are as below.
- Access procedure of ACTBT bit of MR3 register
- Issuance procedure of stop condition
Fixed IAR serial fgets fgetc
Add support for mDot with STM32F411RE processor
[HAL][K20D50M] Serial baudrate improvements / clk_freqs.h fix

Three changes, first it fixes:
https://github.com/mbedmicro/mbed/issues/761 (which was reported
slightly wrong because K20 has again different clocking from KLXX for
uarts).

Second it adds mcgpllfll to clk_freqs, which again is different for K20
compared to KLXX .

Finally it adds the fractional baudrate divider for more accurate serial
baudrates.
Moved IAR serial differences to retarget.cpp
Merge pull request #774 from Sissors/ksdk

Targets: K20D50M - Serial baudrate improvements / clk_freqs.h fix
Merge pull request #772 from mbrudevoldlpd/master

Add support for mDot with STM32F411RE processor
Merge pull request #762 from masaohamanaka/master

Targets: RZ_A1H - Fix some bugs about I2C, SPI, Interruptin and add terminal definition of user button.
Merge pull request #760 from bcostm/master

Targets: NUCLEO_F072RB/F091RC - Remove the call to Systick
Merge pull request #770 from GustavWi/iar_mbed

Fix IAR serial fgets fgetc

Taken from PR #770:
setbuf(_file, NULL), and std::setvbuf(_file,NULL,_IONBF,NULL) should both give an unbuffered stream (the data is directly written to the input buffer). IAR sets a buffer anyway of size 512 bytes for these calls. Calling setvbuff(_file,buf,_IONBF,NULL) with a buffer that is not a NULL pointer sets the buffer to size one. Which means that as soon as a char is read it is written to the real buffer. If people are interested in looking at this further they can look at the files under ARM/src/dlib: fgets.c, fflush.c, xfrpep.c and xfwprep.c
Targets: Freescale KSDK - extern } syntax error fix
Merge pull request #776 from 0xc0170/fix_issue#765

Targets: Freescale KSDK - extern } syntax error fix
Fixed linker files (Ram size on one) and for the rest increased the heap and stack size