Added base class for creating grid and made everything involving grids inherits from here

regtest/analysis/rt-histo/analysis.0.fesA1.reference

regtest/analysis/rt-histo/fesA1.reference

regtest/analysis/rt-histo/fesA1u.reference

regtest/analysis/rt-histo/fesA2.reference

regtest/analysis/rt-histo/fesA2u.reference

regtest/analysis/rt-histo/fesA3.reference

regtest/crystallization/rt-wcsurface2/plumed.dat

...t/multicolvar/rt-dens-average/analysis.0.dens1b.reference

regtest/multicolvar/rt-dens-average/dens1.reference

regtest/multicolvar/rt-dens-average/dens1b.reference

regtest/multicolvar/rt-dens-average/dens1ba.reference

regtest/multicolvar/rt-dens-average/dens2.reference

regtest/multicolvar/rt-dens-average/dens5.reference

regtest/multicolvar/rt-dens-average/dens5a.reference

regtest/multicolvar/rt-dens/analysis.0.dens2b.reference

regtest/multicolvar/rt-dens/dens2.reference

regtest/multicolvar/rt-dens/dens2b.reference

regtest/multicolvar/rt-dens/dens4.reference

regtest/multicolvar/rt-dens/interpol.reference

src/analysis/Histogram.cpp