fixing problem when reading a FROMFILE distribution in parallel. Now the number of particles is correct

throw error if optimizer expression parser doesn't return successfully or if not whole expression has been parsed

Opal maps

See merge request !42

if Enge function is reversed (yields 0 for small z instead of 1) then correct it instead of throwing an exception

automatically count the number of particles in a FromFile distribution and throw an exception if it isn't equal to the number in the first line