released version of weighted balancing

doc/src/balance.txt

doc/src/fix_balance.txt

examples/balance/log.27Sep16.balance.bond.fast.g++.4

examples/balance/log.27Sep16.balance.bond.slow.g++.4

examples/balance/log.27Sep16.balance.clock.dynamic.g++.4

examples/balance/log.27Sep16.balance.clock.static.g++.4

examples/balance/log.27Sep16.balance.g++.4

examples/balance/log.27Sep16.balance.group.dynamic.g++.4

examples/balance/log.27Sep16.balance.group.static.g++.4

examples/balance/log.27Sep16.balance.kspace.g++.4

examples/balance/log.27Sep16.balance.neigh.dynamic.g++.4

examples/balance/log.27Sep16.balance.neigh.rcb.g++.4

examples/balance/log.27Sep16.balance.neigh.static.g++.4

examples/balance/log.27Sep16.balance.var.dynamic.g++.2

examples/balance/runnew.sh

src/balance.cpp