Do not return void from constructor (error with clang-503.0.38)
Do not use va_start macro with variable reference

This is undefined according to the standard and is a warning with clang-503.0.38.
Workaround for “format string is not a string literal” warning
Full implementation of ‘labels’ property
Update license year

Fix outdated copyright year (updated to 2014).
The copyright year was out of date. Copyright notices must reflect the current year, so this commit updates the listed year to 2014.

See http://www.copyright.gov/circs/circ01.pdf for more info.