Remove pragmas for non-standard struct packing in the public API

These pragmas specified that structs should be packed in a way
different from the normal way defined by the current platform ABI.
Since these pragmas are in headers part of the public API, and the
pragmas are nonstandard, this is a portability and compatibility
hazard (all code calling the library need to have the same support
for the nonstandard pragma).

Additionally, accessing unaligned struct members (as produced by this
tight struct packing) can give reduced performance or even lead to
crashes on platforms that require strict alignment.

The only theoretical possible benefits of using the pragma are either
matching a certain struct layout defined in some other, fixed ABI
(but since this is an interface defined by this library itself, there's
no such prior binary interface that needs to be matched), or to reduce
the memory usage by packing the structs tighter (where the reduction
would be marginal at best).
Get rid of trailing whitespace in the platform makefiles
Remove trailing whitespace in comments

The astyle cleanup keeps trailing whitespace within comments,
but the whitespace here is not significant nor intentional
and thus should be removed.
Update the readme with current platform support

Both 32 and 64 bit is supported, on windows, linux and OS X,
including x86 assembly code.
Merge pull request #100 from mstorsjo/trailing-whitespace-cpp-comments

Remove trailing whitespace in comments
Merge pull request #98 from mstorsjo/trailing-whitespace-platform

Get rid of trailing whitespace in the platform makefiles
Merge pull request #107 from mstorsjo/update-readme

Update the readme with current platform support
Merge pull request #88 from mstorsjo/remove-pragma-pack

Remove pragmas for non-standard struct packing in the public API
Merge pull request #1 from cisco/master

update from upstream