New version 0.97 . First attempt to estimate force of mortality

New version 0.97 . First attempt to estimate force of mortality
directly from the data i.e. without the need of knowing the health
state at each age, but using a Gompertz model: log u =a + b*age .
This is the basic analysis of mortality and should be done before any
other analysis, in order to test if the mortality estimated from the
cross-longitudinal survey is different from the mortality estimated
from other sources like vital statistic data.

The same imach parameter file can be used but the option for mle should be -3.

Agn�s, who wrote this part of the code, tried to keep most of the
former routines in order to include the new code within the former code.

The output is very simple: only an estimate of the intercept and of
the slope with 95% confident intervals.

Current limitations:
A) Even if you enter covariates, i.e. with the
model= V1+V2 equation for example, the programm does only estimate a unique global model without covariates.
B) There is no computation of Life Expectancy nor Life Table.