games/rigg 1.1 OpenBSD

rigg serves as a thin, OpenBSD-adapted runtime wrapper for independent games based on certain engines. rigg handles visibility of files by using unveil(2) to hide those that conflict with execution on OpenBSD. This solves a common problem with commercial games based on open-source frameworks like FNA, LibGDX, or HashLink. In addition, rigg also enforces a minimum-necessary filesystem view by default via unveil(2). Some basic engine configuration for OpenBSD like dllmap for mono(1) is included.