support GCC_ARM for LPC4330_M4

 I have a simple test using LPC4330-Xplorer board of NGX Technologies.
LED blink test is OK. DigitalOut class and wait function are used for the test.


* Linker script is based on LPC1768
     number of NVIC is 16 (CORE) + 53 (M4 in LPC43xx) = 69,
    therefor, reserve at the top of RAM0 (address:0x10000000)
    to relocate NVIC vector table
* startup file is based on startup_ARMCM4.S in CMSIS V3.20
     change NVIC name for cortex-M4 of LPC43xx
* add GCC_ARM for LPC4330_M4 in python scripts
* add some descriptions for GCC_ARM