Fix extra data mistakingly "extracted" from raw Deflate streams

Hi, I think there's a bug here.

Per the [BlockFile docstring](/blob/master/src/binwalk/core/common.py#L256), `read_block()` can return **more** than `dlen` bytes of data, by peeking, and this is intended feature.

However, we don't want the peek'd bytes injected into the stream being decompressed -- as the next `read_block()` call will pull them again!

Take a ~1.5 MiB deflated file to test: `binwalk -X` will extract a slighly larger file than a plain `zlib.decompress(-15)` would. (This, exactly, was how this bug bite me.)

Hope this fix is simple enough to be merged easily! Cheers.

Add Adobe Flash's SWF file (the uncompressed variant)

CSR Bluecore DFU (firmware update) file format

Xilinx FPGA bitstream

Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>

Reference: http://wwwimages.adobe.com/content/dam/Adobe/en/devnet/swf/pdf/swf-file-format-spec.pdf Chapter 2 "The SWF header"

Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>

Improve WDK-support, fix common issues

This reverts commit f6b8665b.

extractor: Improved warning for when the external extractor is not found, for issues such as devttys0/binwalk#245