Add utility to update license header information

[koomie]

This PR adds a make license target to the build system that will update source code header files using the license text contained within the top-level LICENSE FILE. To do this, delimiters are used to tag the begin/end of the license in each relevant file. In our case, the delimiters are comment characters followed by "bl" or "el. Example below:

##############################################################################bl
# <SNAZZY LICENSE HERE>
##############################################################################el

The utils/update_license.py script scans for these delimiters and inserts the relevant text in-between so that we can just change the yearly copyright in one place.

Using this addition, the PR also updates yearly copyright notices across a number of source code files.