diagonals 0.4.0
===================
* various small fixes
diagonals 0.3.0
===================
* replace all previous functions with fatdiag
* add fatdig <- function
diagonals 0.2.0
===================
* add support for replacement other than 0 (zero)
* break out rectangles to separate functions: rectangle_matrix() and minus_rectangle_matrix()
diagonals 0.1.0
===================
* block_matrix(): for extracting block diagonals
* minus_block_matrix(): for dropping block diagonals
* add support for non-square matrices