mirrormatrix: Rotate and swap a boggle square.
In vdweijer/games: Functions for word games.

This function creates eight possible versions of a boggle square.

1	mirrormatrix(x)

`x`	Must be the square of an integer. Defaults to 9.

`m0`	No change (123 456 789)
`m1`	Flipped horizontally (789 456 123)
`m2`	Flipped vertically (321 654 987)
`m3`	Flipped along the topleft diagonal (147 258 369)
`m4`	Flipped along the topright diagonal (963 852 741)
`m5`	Rotated left once (369 258 147)
`m6`	Rotated left twice (987 654 321)
`m7`	Rotated left three times (741 852 963)