BinDeps integration

Builds from source on Unix, downloads binaries on Windows, basic functionality appears to work.
Haven't tested this on Mac, could eventually use a Homebrew formula and supply bottles for users who don't have compilers installed.

Fixes part of #6, would be a good idea to turn the examples into tests, set up Travis, etc.

The Windows binaries were built from Cygwin as follows
```
../configure --enable-shared --host=i686-w64-mingw32 --prefix=$PWD/usr
make LDFLAGS="-no-undefined -avoid-version"
make LDFLAGS="-no-undefined -avoid-version" install
```
for 32 bit, or replacing `i686` with `x86_64` for 64 bit.