Merge pull request #93 from cesanta/iobuf

Factor out iobuf into it's own module and increase test coverage
Added convenience macro NS_STR
Merge pull request #110 from cesanta/NS_STR

Added convenience macro NS_STR
Generating docs for structures
Merge pull request #109 from cesanta/structs

Generating docs for structures
Better logic for calculating body length
Merge pull request #111 from cesanta/cloud

Better logic for calculating HTTP body length
Added iobuf_prepend