safer flag management, allow only supported flags to be used
typo fixes
update autogen files
add test for managed flags
pep8 clean
typo fix
move flag manegement internals to pxd file
pep8 clean
move flag mangement internals to pxd
pep8 clean
replace import * by clear list of needed import
update autogen files
make flag management code consistent with NFFT code