Added support for displaying code with the lstlisting package. Added support

for a multi line title.

Makefile:
- Expanded the clean command.

presentation.tex:
- Added an example code frame.

beamerthemelumc.sty:
- Enabled numbering of figures and tables.
- Added settings for displaying code, fixed references in captions of code and
  fixed increasing of the listing counter in an overlay.
- Made the title multi line with the use of a minipage.