Ported to OpenBSD.

Make build work on NetBSD

NetBSD's character class test macros are defined such that they produce
a compiler warning when given a char argument. Adding a cast to the call
fixes this.

CLOCK_THREAD_CPUTIME_ID is a linux-specific timer. On NetBSD, the best
way to get timer information appears to be getrusage, which happens to
be fairly cross-platform.

Made mono tool only get loaded when the dotnet bindings are getting built

Fix #49 stringmap segfault

Fix left-recursion with packrat

Added FreeBSD port

C++ bindings

C++