Wiki-style links

[srid]

Part of #312

Replace autolinks with Wiki links (see below), making them the default. Autolinks will be supported for backwards compat.

• <foo?cf> replaced by [[foo]]
• <foo> replaced by [[[foo]]]
• <z:zettels?tag=xyz> replaced by [[[z:zettels?tag=xyz]]]

In particular note that [[[...]]] makes the link a folgezettel, whereas [[..]] makes it a cf. This applies to full URI queries too.

The following are outside the scope of this PR:

• {{..}} style links
• Plain markdown links

Tasks,

• Working prototype
• Complete, and refactor, implementation
• Add unit test coversage
• Replace all links in ./guide, and update documentation

[vcavallo]

In case it's helpful for anyone in the future, these sed snippets should help with converting your existing <asdf.md?cf> and <asdf.md> style links to the new bracket-style. These worked for me but are largely untested, so be careful, backup your data, and your mileage may vary:

# use from within the directory where your .md files reside.
# for ?cf links:
sed -E "s:<([a-zA-Z0-9.]*)\?cf>:[[[\1]]]:g" *.md

# for standard links:
sed -E "s:<([a-zA-Z0-9.]*)>:[[\1]]:g" *.md

These will also change any other text that is wrapped in < >, so beware of that, as well.

In case you're like me and not a sed expert, after running one of the above commands and determining that the output looks good (the above will output to standard out, but not change anything in your files), add -i'' to the line, as in:

sed -E -i'' "s:<([a-zA-Z0-9.]*)>:[[\1]]:g" *.md

...which will change your files in-place 1. I recommend using git and careful diffing to make sure this is doing what you want. Good luck!