GitLab

Switched exception constants to const char * const (from const std::string) so we don't have to construct them all in every translation unit, and switched the exception class to derive from std::runtime_error (so it handles what() for us)

Added Anchor() regex (so that we're not just using Alphanumeric to match anchors), but it's still not 100% right (it shouldn't allow non-printable characters, e.g.). Also fixed a test that was broken along these lines (if a colon immediately follows an anchor, it's part of the anchor)

Moved all the includes to a subfolder yaml-cpp so they don't interfere with other libraries' includes

Refactored the traits a bit, and added displaying the key to string and numeric key not found errors

Fixed bug in anchors with no content. This involved refactoring the 'implicit sequence' concept (where a map and a sequence start on the same indent, but we read the sequence as more indented since the '-' is visually an indent).

Switched from loading test files to testing specific parsing constructs. The tests don't fully cover the span (eventually I'll add more, maybe), but there's a bunch there.
More to the point, the yaml-reader program doesn't do any file IO, so it doesn't require a specific working directory.