add an example to study the _recoding inbreeding_ phenomenon (dragoon/komodo!97)

this MR adds `examples/inbreeding.rs` which allows to do two things
- _naive recoding_: in order to generate a new random shard, we first $k$-decode the whole data and then $1$-encode a single shard
- _true recoding_: to achieve the same goal, we directly $k$-recode shards into a new one

## the scenario
regardless of the _recoding strategy_, the scenario is the same
1. data is split into $k$ shards and $n$ original shards are generated
2. for a given number of steps $s$, $k$ shards are drawn randomly with replacement and we count the number of successful decoding, given a measure of the _diversity_, $$\delta = \frac{\#success}{\#attempts}$$
3. create a new _recoded shard_ and add it to the $n$ previous ones, i.e. $n$ increases by one
4. repeat steps 2. and 3. as long as you want
 
## results
![inbreeding](/uploads/b81614abcae01b7c915435aa87ccaec0/inbreeding.png)