fails on mdbook 0.5

[anarcat]

mdbook-linkcheck fails to run with a mdbook 0.5 backend:

 INFO Running the linkcheck backend
 INFO Invoking the "linkcheck" renderer
Error: Unable to parse RenderContext

Caused by:
    missing field `sections` at line 1 column 792
ERROR Renderer exited with non-zero return code.
ERROR Rendering failed

you should be able to reproduce with this containerfile:

FROM rust:latest

# copied over from the rust base image, no this is not inherited
ENV RUSTUP_HOME=/usr/local/rustup \
    CARGO_HOME=/usr/local/cargo \
    PATH=/usr/local/cargo/bin:$PATH

# install packages
RUN cargo install mdbook mdbook-linkcheck

COPY . /srv/mdbook

RUN mdbook build /srv/mdbook

a simple mdbook init to create the basic book structure, and a book.toml that enables the extension.

[schilkp]

Opened a PR to fix this: #98