Copyright year updates (things touched in 2015)

Copyright year updates (things touched in 2015)

Update current year in docs and banner copyright in src/src/globals.c

Rest of changes from:

    vi $(git whatchanged --since=2015-01-01 | grep '^:100' | sed -n 's/^[^M]*M//p' | sort -u | fgrep -v test/)

Note that there are a lot of changes made because of const propagation;
I opted to include the copyright year updates in that, but we could be
doing a better job with who gets the copyright credit for these changes.

Changes visible with:

    git diff $(git rev-list -n1 --before="2015-01-01" master)