Some test files failed to build as the go module "replace" doesn't work
with test and internal packages yet.
The other tests need updates to the testdata.
The github markdown interpreter has been changed such that it no longer
allows spaces in between the brackets and parenthesis of links and now
requires a newline in between anchors and other formatting. This
updates all of the markdown files accordingly.
While here, it also corrects a couple of inconsistencies in some of the
README.md files.
