This commit allows to enable/disable the txtsnd shell command. The
command is used to send strings over L2 in GNRC. Until now the command
was automatically enabled if GNRC and shell_commands were present, which
may lead to confusion if no L2 packet handler is registered.
As discussed in #2725, this commit renames a number of stacksize constants to
better convey their intended usage. In addition, constants for thread priority
are given a `THREAD_` prefix. Changes are:
* KERNEL_CONF_STACKSIZE_PRINTF renamed to THREAD_EXTRA_STACKSIZE_PRINTF
* KERNEL_CONF_STACKSIZE_DEFAULT renamed to THREAD_STACKSIZE_DEFAULT
* KERNEL_CONF_STACKSIZE_IDLE renamed to THREAD_STACKSIZE_IDLE
* KERNEL_CONF_STACKSIZE_MAIN renamed to THREAD_STACKSIZE_MAIN
* Move thread stacksizes from kernel.h to thread.h, since the prefix changed
* PRIORITY_MIN renamed to THREAD_PRIORITY_MIN
* PRIORITY_IDLE renamed to THREAD_PRIORITY_IDLE
* PRIORITY_MAIN renamed to THREAD_PRIORITY_MAIN
* Move thread priorities from kernel.h to thread.h since the prefix has changed
* MINIMUM_STACK_SIZE renamed to THREAD_STACKSIZE_MINIMUM for consistency
squash: driver: fixed typo to pass doccheck
squash: driver: bug fixes after test
squash: adapted Makefiles for correct build behaviour
restructured, no spi interaction in isr anymore
major bugfixes and restructurization
comments addressed
introduce new netconf option, ..AUTOCCA
squash: minor bugfix and add auto-init mechanism
squash: minor fixes to make travis happy
