Use Boost.Program_options instead of hand written argument parsing code

We should unify argument parsing and configuration code by using [Boost.Program_options](http://www.boost.org/doc/libs/1_60_0/doc/html/program_options.html) instead of [hand written argument parsing](https://github.com/ooxi/violetland/blob/master/src/program.cpp#L1921) and [ConfigFile](https://github.com/ooxi/violetland/blob/master/src/system/ConfigFile.h).
