option of chosing the number of ticks

the option is call nticks and can be used as
plot(timeseries,'nticks',12) and also works for bar except that in that
case it has to come immediately after the time series object
bug correction in the substitution of definitions
expanded the capabilities of function evaluator

this is because of the new symbolic differentiation engine
cosmetic change
transform cell of strings to functions
Implementation of new symbolic differentiator
shortened load_data
corrected bug introduced earlier today

Issue comes from substituting rise_sym to planar. rise_sym was still
used by the parser.
clean up of a few obsolete files
updated the fs2000 example
updated howto for fs2000
Cosmetic changes
Deleted comment
removed comments in planar
fs2000 dynare log