Use pointer to stream instead of reference to stream to allow for null streams
Added write_sampler_state for general implementation display
Don't clear vectors before appending param names and values
Added sample output method
Intermediate reworking of command to use mcmc_writer
Print diagnostic information
Merge branch 'master' into mcmc_writer

Conflicts:
	src/stan/gm/command.hpp
Change command name to reflect options besides nuts
Take in unconstrained parameter names when generating diagnostic headers
Fixed creation/use of diagnostic stream, use mcmc_writer for all sampling output
removing sign compare warning from src/mcmc/hmc/hamiltonians/diag_e_point.hpp
Added mcmc_writer class, which somehow disappeared from the branch
Parse updated output format, grab and print timing as well as ESS/time
Parse updated output format
Updated reader tests
New MCMC Writer tests
MCMC writer test
Tweaked MCMC writer diagnostic method name
Add const qualifier to read-only methods
Added empty line to end of timing output, update tests