Merge branches 'master' and 'develop' of github.com:jamalex/ka-lite into develop
Merge branch 'develop' of github.com:jamalex/ka-lite into develop
Fixed minor translation-related bug in video download page.

One of the translatable strings was missing the trans tag. Added context
for the translation of the word 'of' so that its meaning is clear.
Fixed bug regarding topic links.

The home page previously displayed a set list of top-level topics,
yet one of these topics has since been moved to a different level
in the topic-tree. The homepage template was changed such that topic
titles are no longer hard coded, but instead populate based on the top-
level topics in topics.json.
Removed topictree.json

This file was no longer being used, but took up a great deal of space
and could be confused with topics.json.
Merge branch 'develop' of github.com:jamalex/ka-lite into develop