Updated original performance test program.

* Updated the original performance_main program.
    * Does no longer depend on pficommon library.
    * Uses C++11 instead.
    * Works with Eigen 3.2.0.
    * Comes with compile instructions, does not need build system.
    * Behaviour probably slightly changed, compared to the original
      version.
Added simple example and performance comparison.

* Added very simple example program that demonstrates how to use Arpaca.
* Added program to compare the performance of Arpack and Eigen.
* Both programs come with compile instructions and do not rely on a
  build system or other dependencies.
Updated arpack_test and build script.

* Waf builds all three programs.
* Updated arpack_test, so that arpack_test builds correctly.
* Updated README.
Fix include for arpaca.hpp.
Merge branch 'improvements'

Conflicts:
	.gitignore