Update to conform with with modern thesis format guidance

[Foggalong]

From @adkbeckett

Updated the package to conform to modern thesis format guidance and institutional nomenclature: Changed the implementation of the declaration to allow it to be edited within the document (and included an example from the University guidance document in the example report); defined environments for lay summary, acknowledgements; added option for a sans-serif font (Computer Modern Bright); added option to declare a short version of the title for headers if the fancyhdr option is used.

[Foggalong]

To maintain backwards compatibility for older documents written with \declaration{} the code had to be slightly updated. With d54bff2 we can now do use that command which produces the same declaration as 58a2da4 and earlier

We can also use the environment as in #12

\begin{declaration}
    {I declare that this thesis has been composed solely by myself and that it has not
    submitted, in whole or in part, in any previous application for a degree. Except where
    stated otherwise by reference or acknowledgement, the work presented is entirely my
    own.}
\end{declaration}

but with an added {...} encasing, a workaround to enable using a command as an environment. This produces the same declaration as in #12

We can also use it as a command with an argument

\declaration{
    This is an example of another declaration.
}

or as an in-line environment

{\declaration This is an example of another declaration.}

both of which produce

[Foggalong]

I've tested this against a couple of example theses and my own which is heckin messy behind the scenes and everything looks to be working as intended. Thanks so much for doing this @adkbeckett!