Changes from LATTICEEASY 2.0 to LATTICEEASY 2.1

None of these changes affect how the program is used or the format of the output, so most users can ignore them.
1. There is a new (undocumented) option intended solely for debugging. If seed<1 the random number function simply returns 0.33, thus eliminating all randomness from the initial conditions. If seed<0 initial Fourier Transforms will not be performed, thus eliminating some of the most significant rounding errors from the initial conditions. Note, however, that the results from using this option are predictable and reproducible, but physically incorrect. This option should only be used for debugging.
2. The function output_initialize() has been eliminated and the variables nfldsout and ext_ are now set in initialize() instead.
3. There was a bug in the histograms_2d() function that sometimes caused it to abort the program. This bug has been fixed.
4. The variable output_interval could be calculated incorrectly for runs that were continued from grid images. This bug has been corrected by moving the calculation after the initialization.
5. The spectra are now the last output to be calculated so that the roundoff errors introduced by their Fourier Transforms don't affect other output functions at that time step.