Extract custom fonts into an extension.

Currently, a lot of our classes have a very large amount of code,
implementing many different features, all mixed together. This is quite
hard to manage and makes the code overly complex.

What I am aiming to do is separate out some of the code that does
related things, offering a better paradigm for implementing new features
that does not clutter the existing code.

As a proof of concept, I am aiming to extract the Custom Fonts support
(which I wrote and therefore know reasonably well) into a set of classes
that separate classes that define anything relating to that particular
feature, so that the rest of the code does not need to know about it.

This is a work in progress: it will take a bit of time to get to the
perfect solution; but it is a step forward in that direction. Probably
things will change as I go along, so nothing is really final yet.
added support for Samsung Multi-Window
fully customisable -> customisable
Ads for Stackoverflow (free advertising for open source projects)
Fix multilined LaTeX within card templates

Fix issue 1935. The mungeQA method is passed a string that has been
stripped of newline characters in the "meat" of the card, but which can
still contain newlines in the templated part. Get mungeQA to handle this
properly; also, switch to case-insensitive matching for [latex] tags.
Remove redundant activities & a service

IntelliJ revealed some activities and a service in the manifest
which are do not exist.  Additionally, SharedDeckerPicker is no
longer used anywhere.  Both of these are therefore worth removing.

Actually remove SharedDeckerPicker as #hssm suggests
Update version number to latest 2.1 build.