The modules `newlib, `newlib_syscalls_default` and `stdio_uart` are now used by default for output to the UART interface. This also reduces the dependency rules.
Some SDK interrupt service routines obviously use malloc/free in the interrupt context. Because the rmutex-based lock/unlock approach of the malloc/free function suite of the newlib does not work in the interrupt context, the SDK memory management functions MUST therefore be used. To use the same memory management functions in RIOT as in the SDK, the malloc/free function suite has to be replaced by wrapper functions.
Changes of ETS task handling require the context switch by software interrupt. The context switch based on interrupt is therefore enabled by default. Furthermore, the number of priority levels are increased due to the new additional thread.
