Changed relatedness.py library to run significantly faster and use less memory by vectorizing operations where possible and reducing redundant calculations.
Modified the documentation on the scripts and the header documentation to be clearer and more accurately reflect what was being calculated.
Modified relatedness_library.py and its tests to reflect the new functions and to add a little more documentation.
Updated the documentation again to reflect the tests of NRI and NTI against phylocom4.2.
Modified the script relatedness.py to update the documentation and the tests to be clearer and handle more cases of error.
Removed unnecessary imports.
Modified two lines to address comments of @wasade.
Removed unnecessary comment line.
Merge pull request #651 from wdwvt1/relatedness_speedup

Relatedness speedup