ext_algorithm.hpp is included using quotes, not angle brackets

I tried using the library on my Ubuntu 12.10 system and ran into another include problem.

The ext_algorithm.hpp header file is being included using the ```#include <ext_algorithm.hpp>``` notation, which looks for the header file only in standard header locations. I switched it to the ```#include "ext_algorithm.hpp``` style, so the preprocessor looks for the header file in the [prefix]/include/maxent directory instead of just looking only in the inlude directories.

Before the change, I got compilation errors in the preprocessor phase. After the change, everything compiles without a problem.