Fix links in imported designs

A lot of the links in the imported designs are broken:

- HotDoc allowed a `[][link]` format that Hugo doesn't understand
- HotDoc allowed relative links without text, which Hugo doesn't handle
- The location of the images and other media has changed
- The format used for internal page references has is different

Additionally, fix up touched links to other Apertis pages to use the
Hugo "ref" shortcode, which reduces the risk of leaving hanging links.

Conversion completed with the following python script:

```

import os
import re
import sys

def url_munge(match):
    url = match.group('url').strip('.')
    if url[0] != "/":
        url = "/%s" % url
    url = url.replace("media", "images")
    link = ("![](%s)" % url)

    return link

def link_munge(match):
    link = match.group('link')
    new = link.replace("(", "")
    new = new.replace(")", "")
    new = new.replace("`", "")
    new = new.replace("?", "")
    new = new.replace(":", "")
    new = new.replace(",", "")
    new = new.replace("–", "")
    new = new.replace("“", "")
    new = new.replace("”", "")
    new = new.replace(".", "")
    new = new.replace(" ", "-")
    new = new.lower()
    new = (" [%s]( {{< ref \"#%s\" >}} )" % (link, new))

    return new

def link_munge_2(match):
    link = match.group('link')
    new = link.replace("#", "")
    new = new.replace("-", " ")
    new = new.replace(".md", "")
    if not "http" in link:
        link = " {{< ref \"%s\" >}} " % link

    new = ("[%s](%s)" % (new, link))

    return new

for filename in os.listdir(sys.argv[1]):
    #print("%s: " % filename)
    with open(filename, 'r+') as file:
        contents = file.read()

        # Hotdoc uses `[][Internal Title]` for internal links whilst Hugo uses `[](#internal-title)`
        pattern = re.compile("\[\]\[(?P<link>.*?)\]")
        contents = pattern.sub(link_munge, contents)

        # Hotdoc allows empty links like `[](url)`
        pattern = re.compile("[^!]\[\]\((?P<link>.*?)\)")
        contents = pattern.sub(link_munge_2, contents)

        # Media links not working
        pattern = re.compile("!\[\]\((?P<url>.*?)\)")
        contents = pattern.sub(url_munge, contents)

        file.seek(0)
        file.truncate()

        file.write(contents)

```

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>