[EXPORT][GCC_ARM] additional linker option for wrap main

Most makefile templates didn't use the -Wl,--wrap,main so that
__wrap_main was not called.
Name of exit function in exit.c

Change the name of the exit function to _exit as suggested in clib
documenation for all gcc_arm toolchains (GCC_ARM and CoIDE)
[NUCLEOs] Improvement of gpio_irq hal

Now it is possible to have multiple interrupt pins on EXTI vectors.
Example:
EXTI0 -> PA_0 or PB_0 or PC_0, ... only 1 pin
EXTI5_9 -> PA_5 and PA_6 and PB_7 and PC_8 and PC_9: up to 5 pins
EXTI10_15: PA_10 and PB_11 and PB_12, ... : up to 6 pins
Revert "[NUCLEO_F103RB] update SystemCoreClock after changing clock settings"
Merge pull request #728 from xiongyihui/revert-724-master

Targets: Revert "[NUCLEO_F103RB] update SystemCoreClock after changing clock sett...
[EXPORT][GCC_ARM] additional linker option for wrap main

Most makefile templates didn't use the -Wl,--wrap,main so that
__wrap_main was not called.
[mbed][rtos][k22f] Add initial FRDM-K22F support
Modified Terminal setting for New GR-PEACH.

Modified Terminal setting of Ethernet and LED PIN for New GR-PEACH.
Tools: Export for nrf51dk and dongle to GCC ARM and uvision
Merge pull request #732 from sg-/k22f_rtos

RTOS: Add initial FRDM-K22F support
Merge pull request #730 from ohagendorf/make_wrap_main_2

Tools: Exporter for GCC_ARM - additional linker option for wrap main
Minor change: added more informative commnet about self.detect_code field in Target class
target detection API added together with detection codes which will be used to determine platform - used mainly by lmtools
Unlocked --db switch. Added Wiki page entry to explain how to use MySQL DB with test suite
Unlocked --db switch. Added check when parsing DB connection string
[NUCLEO_F030R8] exporter for gcc and coide
[NUCLEO_F072RB] exporter for gcc and coide
[NUCLEO_F0xx] build_travis and build_release

Add NUCLEO_F030 and NUCLEO_F072 to build_travis. Extend toolchainlist of
both targets in build_release.
Merge pull request #734 from 0xc0170/dev_nrf51_xx_exporters

Tools: Export for nrf51dk and dongle to GCC ARM and uvision
Merge pull request #737 from ohagendorf/NUCLEO_F030R8_F072RB_export_gcc_coide

Tools: NUCLEO_F030R8, NUCLEO_F072RB - export to gcc_arm and coide