log likelihood and derivatives for Geom distribution

`llikGeom(x, prob, full = FALSE)`

- x
variable distributed by a geom distribution

- prob
probability of success in each trial.

`0 < prob <= 1`

.- full
Add the data frame showing x, mean, sd as well as the fx and derivatives

data frame with `fx`

for the log pdf value of with `dProb`

that has the derivatives with respect to the `prob`

parameters at
the observation time-point

```
llikGeom(1:10, 0.2)
#> fx dProb
#> 1 -1.832581 3.75
#> 2 -2.055725 2.50
#> 3 -2.278869 1.25
#> 4 -2.502012 0.00
#> 5 -2.725156 -1.25
#> 6 -2.948299 -2.50
#> 7 -3.171443 -3.75
#> 8 -3.394586 -5.00
#> 9 -3.617730 -6.25
#> 10 -3.840873 -7.50
```