A number of tests insist that the number of thread priority levels is 16. However, when using the WiFi interface, a number of high priority threads are required to handle the WiFi hardware. In this case, the number of thread priority levels must be 32. Solves the problem of tests `tests/shell`.
Removes the dependency of the module riot_freertos from module xtimer. This avoids that xtimer is used even if it is not really needed which in turn occupies the first timer device and tests/periph_timer fails.
ESP32 log output was always tagged with additional information by default. The tag consists the type of the log message, the system time in ms, and the module or function in which the log message is generated. By introducing module `esp_log_tagged`, these additional information are disabled by default and can be enabled by using module `esp_log_tagged`.
Log module of ESP32 supports colored log outputs when module `esp_log_color` is enabled. The generation of colored log outputs is realized by a extending the bunch of macros with an additional letter indicating the type of log message,
For the implementation of the colored log output, two versions of the bootloader are introduced, one version with colored log output and one version without colors.
The modified version esptool.py from RTOS SDK that is required for flashing an image, is now placed in `dist/tools/esptool.py` and used directly from there. The advantage is that `esptool.py` hasn't to be installed explicitly anymore. Having RIOT is enough. The documentation is adapted accordingly. The oly prerequisite is that python and the pyserial module are installed.
In vendor startup code, initialization function were called as parameters of assert statement. With DEVELHELP, they are not called since the assert macro does nothing.
To make the migration progress to the new RTOS SDK easier, the new toolchain was renamed to xtensa-esp8266-elf. This makes it possible to have the new and the old toolchain installed in parallel.
If the WiFi module is used, a number of high priority tasks is created. To void priority collisions with netdev drivers, the number of priorities SCHED_PRIO_LEVELS has to be increased to 32. But in other cases, the default number should be used, also to keep automatic tests working.
Moved macros and static inline helper functions needed to access ATmega GPIOs
to cpu/atmega_common/include/atmega_gpio.h in order to reuse them for the
platform specific low level part of the Neopixel driver.
