matrix_to_tibble: Convert matrix to tibble.
In Hide-Fun/teco:

Convert matrix to tibble.

1	matrix_to_tibble(.mat, .row = FALSE, .rowname = NULL)

`.mat`	matrix
`.row`	logical, convert rowname to column?
`.rowname`	character, rowname.

mat <-
   matrix(data = rnorm(100),
          nrow = 10,
          ncol = 10)

rownames(mat) <- sprintf("com_%d", 1:10)

# convert to tibble.
matrix_to_tibble(.mat = mat, .row = FALSE)
# move rownames to column.
matrix_to_tibble(.mat = mat, .row = TRUE, .rowname = "com")