Fix unaligned access to zip data. There's still a corner case where i…

…t could fail (if we do not reach the directory signature on the first try, we move only one byte backward) but it seems fine as far as I could test so far. #190

src/zip.cpp

@@ -45,10 +45,10 @@ namespace zip
       }
       pbPtr = pbGPBuffer + (256 - 22); // pointer to end of central directory (under ideal conditions)
       while (pbPtr != static_cast<byte *>(pbGPBuffer)) {
-        if (*reinterpret_cast<dword *>(pbPtr) == 0x06054b50) { // check for end of central directory signature
+        if (*reinterpret_cast<word *>(pbPtr) == 0x4b50 && *reinterpret_cast<word *>(pbPtr+2) == 0x0605) { // check for end of central directory signature
           wCentralDirEntries = *reinterpret_cast<word *>(pbPtr + 10);
           wCentralDirSize = *reinterpret_cast<word *>(pbPtr + 12);
-          dwCentralDirPosition = *reinterpret_cast<dword *>(pbPtr + 16);
+          dwCentralDirPosition = *(reinterpret_cast<word *>(pbPtr + 16)) + (*(reinterpret_cast<word *>(pbPtr + 18)) << 16);
           break;
         }
         pbPtr--; // move backwards through buffer