Revert "Adjust the encoding m_pos uses when pointing past the last element"

Summary: Breaks several OSS frameworks

Reviewed By: @ptarjan

Differential Revision: D1429426
Re-record twig

Summary: Broken by PHP_VERSION change.

Reviewed By: @ptarjan

Differential Revision: D1429477
reformat docs, extend .gitignore

Summary: * configure: clean spaces, tab's
* .gitignore: ignore the subfolder "build", build/binary files
* README.md: [related link](https://github.com/denji/hhvm/commit/9fa7fcba90f3e0aacf44929385f91aad762e9ac3?short_path=04c6e90#diff-04c6e90faac2675aa89e2176d2eec7d8)
Closes #3060

Reviewed By: @ptarjan

Differential Revision: D1427535

Pulled By: @fredemmott