Html5validator

- a fix for Cygwin thanks to this [PR](https://github.com/svenkreiss/html5validator/pull/20)

vnu.jar` updated to 16.6.29 ([PR](https://github.com/svenkreiss/html5validator/pull/19))

Fixes for Python builds on Travis CI.
See v0.2.0 release notes.

- `--ignore`, `--ignore-re`: ignore messages containing an exact pattern or
matching a regular expression (migration from version 0.1.14: replace `--ignore` with `--ignore-re`)
- curly quotes and straight quotes can now be used interchangeably
- change Java stack size handling (introduced the new command line options `-l`, `-ll` and `-lll`)
- update vnu.jar to 16.1.1 (which now requires Java 8)