expose bug: disabling offsets broken
disabling offsets works again
docstring for _read_beginning
ensure that the file doesn't actually have any offsets
check that trying to append to a file without offsets fails
add missing NotEnoughSpace exception
check that appending to a file with no space left fails
refactor testing append code
add missing return value in docstring
fix setting typesize in append
squeeze blosc_args through array prep method too
fixup comment
test mixing shuffle settings
return the total number of written chunks on append
an extensive test for mixing compression settings