apps/system/netdb would not build unless CONFIG_NETDB_HOSTFILE was defined because it needed gethostbyname.  Noted by OrbitalFox

apps/examples/usbserial: Can now be run as an NSH builtin-function. Now uses a configurable IO buffer size

apps/examples/can:  In extended ID mode, need to set some unused bits to zero or otherwise the memcmp() will fail on comparison with the returned value

apps/tools/mkkconfig.sh:  The top-level Kconfig file is not auto-generated.  The autogenerated Kconfig file will be constructed so that every second level directory that contains a Kconfig file will automatically be sourced

webserver:  Allow to build webserver as an application

Signed-off-by: Anton D. Kachalov <mouse@yandex-team.ru>

readline():  A a configuration option to enable/disable command line history; Additional cosmetic changes from code review

Added command history using up/down arrow keys.

Change the name of the local variable sigset to set to prevent name collisions with the function of the same name

Readline: Fix a configuration dependency.  If we are not echoing to the console, then we cannot support tab completion

readline/NSH: Extend the tab-completion logic so that NSH commands can also be completed by pressing the tab key

readline: Update initial readline commit -- make option configurable.  Add an interface to de-couple the readline implementation from NSH.  Misc. updates for coding style

Unix style TAB compleition, for builtin apps only

OS test: Sporadic test now emits a message if the max_repl configuration is too small for the test to work reliably

OS test: add some locking and unlocking of the scheduler to the sporadic scheduler test in order to test a few more cases