Merge pull request #8 from eroux/master

new functions for modules and doc updates
Merge pull request #9 from eroux/master

doc update
Update Makefile to reflect Changes->NEWS
Merge pull request #1 from lualatex/master

sync with current
make user whatsit generators accept an optional argument of type node
do some basic validation on a node before accepting it as whatsit
doc: Some user whatsit related documentation fixes.
Merge pull request #11 from eroux/master

Closing issue #10
Merge pull request #12 from sh2d/master

Some user whatsit related documentation fixes.
Merge branch 'master' into whatever
add function to retrieve attribute unset value
Merge pull request #13 from phi-gamma/master

make unset value accessible by a function
make user whatsit generators accept an optional argument of type node
have ``new_user_whatsit()`` accept prototype as first argument
document alternate behavior of ``new_user_whatsit()``
reintroduce checks for prototype validity
Merge pull request #15 from phi-gamma/master

update with requests by @sh2d
Merge pull request #8 from lualatex/master

sync with lualatex repo