Grand-canonical version, main_gc.f90. In progress
Grand-canonical: increase max_iterations in root bisection routine

  - Grand-canonical calculations (main_gc.f90) seem to work well now.
    They agree well with canonical calculations at low temperatures and are
    close at high temperatures.
main_proj.f90: Free fermions via particle number projection (works!)
Change the code to only calculate quantities for one species
Add calculation of the energy to particle-number-projection code

  - Tested against the multiprecision code -- works.
Update makefile; change a few comments in main_gc.f90
Rename files
Update test data
Try to generalize dimension (haven't tested yet for d.ne.3)