Latest changes:
    * Bumped version number to 1.2.8
    * As suggested by Jim Clausing. Added computation of MD5, SHA-1, SHA-256 and SHA-512 on a per-section basis. The results are always reported when invoking the dump_info() method in the PE instance. SHA-256 and SHA-512 are calculated only in Python 2.5 onwards which includes them in the hashlib module. The SectionStructure_ instances now sport the following methods: get_hash_sha1(), get_hash_sha256(), get_hash_sha512(), get_hash_md5()
    * Faster entropy calculation by Gergely Erdelyi
    * Added some intelligence handling unicode strings in the resources information. Strings in the resources seem to always be Pascal style, added support for those
    * Changed some loops iterating using range() to use xrange() instead. It will make the code more robust/faster whenever invalid large numbers of elements are specified in different arrays
    * As per c1de0x suggestion, added set_data() method to SectionStructure_
    * Added get_entropy() method to SectionStructure_. Now it's only calculated on demand or when doing a dump_info()
    * c1de0x pointed out a redundant length check in __unpack_data__ and __unpack__. Now the exception raised by the latter is caught by the former and a warning added if a structure can't be parsed because of missing data
    * Fixed bug parsing export directory. Warning messages are added if it's found to be invalid
    * Fixed bug parsing the IAT. Some broken samples could crash pefile. The invalid IAT is now reported in the warnings
    * New method: relocate_image(new_ImageBase) will apply the relocation information, if any, to the image
    * get_memory_mapped_image() now supports and additional keyword argument, ImageBase_. By specifying an address it will return a data relocated (if the PE contains relocation information) as if it had been relocated to the new ImageBase_
    * Added full family of bytes/word/dword/qword manipulation methods (needed by the relocation functionality):
    * get_data_from_dword(dword), get_dword_from_data(data, offset), get_dword_at_rva(rva), get_dword_from_offset(offset), set_dword_at_rva(rva, dword), set_dword_at_offset(offset, dword)
    * get_data_from_word(word), get_word_from_data(data, offset), get_word_at_rva(rva), get_word_from_offset(offset), set_word_at_rva(rva, word), set_word_at_offset(offset, word)
    * get_data_from_qword(qword), get_qword_from_data(data, offset), get_qword_at_rva(rva), get_qword_from_offset(offset), set_qword_at_rva(rva, qword), set_qword_at_offset(offset, qword)
    * set_bytes_at_rva(rva, data), set_bytes_at_offset(offset, data)