Add woff2 to src/third_party

third_party/woff2/README.md

+This is a README for the font compression reference code. There are several
+compression related modules in this repository.
+
+brotli/ contains reference code for the Brotli byte-level compression
+algorithm. Note that it is licensed under an Apache 2 license.
+
+src/ contains the C++ code for compressing and decompressing fonts.
+
+# Build & Run
+
+This document documents how to run the compression reference code. At this
+writing, the code, while it is intended to produce a bytestream that can be
+reconstructed into a working font, the reference decompression code is not
+done, and the exact format of that bytestream is subject to change.
+
+## Build
+
+On a standard Unix-style environment:
+
+```
+git clone https://github.com/google/woff2.git
+cd woff2
+git submodule init
+git submodule update
+make clean all
+```
+
+## Run
+
+```
+woff2_compress myfont.ttf
+woff2_decompress myfont.woff2
+```
+
+# References
+
+http://www.w3.org/TR/WOFF2/
+http://www.w3.org/Submission/MTX/
+
+Also please refer to documents (currently Google Docs):
+
+WOFF Ultra Condensed file format: proposals and discussion of wire format
+issues (PDF is in docs/ directory)
+
+WIFF Ultra Condensed: more discussion of results and compression techniques.
+This tool was used to prepare the data in that document.