also fix and improve some of the existing

Make sendto() and accept() interfaces conform to POSIX,

make sendto() and accept() interfaces conform to POSIX, doesn't change anything as addrlen is unused anyway

* assert active_thread pointer before saving it

* fixed documentation in irq.h
* moved tools folder to dist
* added check for disk space in build_gnuarm script
* fixed gcc check in this script, too

* updated some makefiles and fixed includes for msb430h

* tidied up sys directory

Add inet_pton and inet_ntop (POSIX.1-2001)

* added some auto dependencies