#Randomize \$SL_n(\mathbb R)\$

Given a positive integer \$n > 1\$, return a random element from \$SL_n(\mathbb R)\$.

###Details
* \$SL_n(\mathbb R)\$ is the set of \$n \times n\$ matrices with determinant \$1\$.
* In theory the output must cover the whole \$SL_n(\mathbb R)\$ (that is, if the RNG you're using was perfect and we could actually represent real numbers).
* We don't require an *uniform* distribution.
* Instead of real numbers it is sufficient to work with floating point numbers.