Fix default setting of default GBP_DAT dir in Makefile
Merge pull request #1 from smutch/makefile_fix

Fix default setting of default GBP_DAT dir in Makefile
USE_FFTW now defaults to being on (to fix some compiler errors).
Added python script for Poole et al 2014 bias model.
Added some documentation to bias_model_Poole2014.py.
Added gbpDir code.
Various changes to accomodate new gadget file processing.  Also fixed a pcounter bug.
Fixed a local Makefile bug.