Release YAML 0.1.8.

[ingydotnet]

It's been over a year since libyaml was released. The mew maintainers have not
yet cut a release. There has been a bunch of work done.

This PR and branch will be used to prepare the release.

We need to make a release checklist. I'm not sure all that is involved in a
release.

There are a number of PRs that probably belong in the release:

• Rename config.h to yaml_config.h to prevent naming conflicts #84 Rename config.h to yaml_config.h to prevent naming conflicts
• Fixed most compiler warnings -Wall -Wextra #78 Fixed most compiler warnings -Wall -Wextra (based on various updates to 0.1.7 #27)
• colon can be in a plain scalar #28 colon can be in a plain scalar (waiting on @flyx review/assessment)
• Use pointer to const for strings that aren't/shouldn't be modified #6 Use pointer to const for strings that aren't/shouldn't be modified
• change dllexport controlling macro to use _WIN32  #66 change dllexport controlling macro to use _WIN32 (need @hanetzer review)
• README: Update libyaml link #64 README: Update libyaml link
• Patch to guard against integer overflow #19 Patch to guard against integer overflow (needs review)
• Add Solaris compilation fix from Perl binding repo. #16 Add Solaris compilation fix from Perl binding repo

Any ideas to make the repo layout better before we release would be
appreciated.

We do need to wait until @flyx returns (a week more I think) so gives us time.

[ingydotnet]

See The Project Plan