phdu: add missing support for TLOGICAL cards
file,hdu: remove low-level API
file,hdu: remove low-level API
header: more doc
header: more docstrings
hdu: more docstrings
card: remove CardType. more docstrings
column: more docstrings
image: more docstrings
image: more docstrings
phdu: more docstrings
tablist: more versatile display format (handles more data types)
Merge branch 'feature/lean-api' into develop