Wave plot using normal prior

#### 1) Creation of new design class log_design_normal_two()
```
des <- log_design_normal_two(30, 30, 0.6, 0.83, 0.83, 0.8, 0.8)
```
What this does?
applies log10 transformation to MV and TV without having to alter underlying code

wave plot using log-t prior

Example 1
```
des <- log_design_normal_two(30, 30, 0.6, -0.08092, -0.08092, 0.8, 0.8)
> prior
Distribution: Log t
Parameters:
locationlog: -0.203
scalelog: 0.0465
lower: 0.1
df: 3
> approx_unimodal(log10(rand(prior,1000000)), -0.5, 0.5)
$dens
[1] "t"
$params
mean sd df
-0.03793412 0.01798629 3.00000000
> prior4
Distribution: t
Parameters:
location: -0.0378887556939152
scale: 0.0312649658848961
df: 3
assurance(des, prior4)
# A tibble: 1 × 4
go stop inter incon
<dbl> <dbl> <dbl> <dbl>
1 0.295 0.142 0 0.563
```
Example 2
```
> des <- design_normal_two(30, 30, 0.6, -0.08092, 0, 0.8, 0.8)
> prior <- dist_logt(-0.203, 0.0465, 0.1, 3)
> qdmtools::approx_unimodal(log10(rand(prior, 100000)), -0.5, 0.5)
Distribution: t
Parameters:
location: -0.0379376141128745
scale: 0.0180681441389967
df: 3
> prior_new <- dist_t(-0.0379, 0.018)
> assurance(des, prior_new)
# A tibble: 1 × 4
go stop inter incon
<dbl> <dbl> <dbl> <dbl>
1 0.289 0.278 0 0.432
```
Example 9
```
des <- design_normal_two(30, 30, 0.6, 0, 0.1761, 0.9, 0.99)
prior <- dist_gamma(4.78, 1.28, 0.1)
> approx_unimodal(log10(rand(prior, 100000)), -0.5, 1)
$dens
[1] "beta"
$params
alpha beta lower upper
8.262214 3.683652 -0.500000 1.000000
> db <- dist_beta(8.26, 3.68, lower = -0.5, 1)
Distribution: Beta
Parameters:
alpha: 8.26
beta: 3.68
lower: -0.5
upper: 1
> assurance(des, db)
# A tibble: 1 × 4
go stop inter incon
<dbl> <dbl> <dbl> <dbl>
1 0.909 0.00278 0 0.0884
```
Example 9
```
> des <- design_normal_two(30, 30, 0.6, 0, 0.1761, 0.9, 0.99)
> prior <- dist_gamma(4.78, 1.28, 0.5)
> qdmtools::approx_unimodal(log10(rand(prior, 100000)), -0.5, 1)
Distribution: Normal
Parameters:
mean: 0.596457274382407
sd: 0.178093152201127
> prior_new <- dist_norm(0.59812, 0.1772004)
> assurance(des, prior_new)
# A tibble: 1 × 4
go stop inter incon
<dbl> <dbl> <dbl> <dbl>
1 0.955 0.000443 0 0.0443
```