More draft 0.3 chapters

[Yaron Kashai <kashai@ieee.org>]

Dear all,

5 new chapters were added to the draft 0.3 download page:

7  - constraints
13 - macros
17 - packing
23 - built in methods
28 - resource sharing control structs (new semaphore and locker chapter)

As usual, please take the time to review and comment.

Best regards,
-- yaron