add pack/unpack support,  does not translate
trying to make stuff translate
some progress, fails tests!, does compile!
Merge branch 'master' into pack_unpack
some fix to enable backup one byte
fix for X format
some fixes,  tests added
clearup tests
Merge branch 'master' into pack_unpack
Don't require an interpreter to run w_array.as_pair.list(space)

Fixes most -A tests in testing/test_phpstruct.py
Correctly handle 'H*' format
Fix W_RDictArrayObject.as_pair_list()
Merge branch 'master' into pack_unpack
fix translation
simplify code
Fix precision issue in unserialize()

Note: convert_string_to_number() seems dodgy. It's definitely wrong here,
and simply using rfloat.string_to_float() fixes the issue.
Fix issue with unpack('H*', ...)
Make pack() tests more systematic
Fix some issues revealed by TestPack.test_pack_numeric()
DRY

Note: PHP has inconsistent warning messages. I think that the
minor incompatibility is worth it.