Until now this file was just checked into the repo, but actually it
should be generated from any.js, struct.js, and timestamp.js. This
change updates the build system to make this happen. To make it work I
also had to remove some C++11 features from embed.cc.
This pull request includes two implementation: C extension and PHP
package. Both implementations support encode/decode of singular,
repeated and map fields.
This could be tidied up significantly, and at some point we will want to parse the markdown and generate more appropriate XML - but this is definitely better than nothing.
Generated code changes coming in next commit.
