Update osx-bootstrap modules to newer versions

libpng, libjpeg, libxml2, and libxslt can all be simply updated to newer
versions.
Update libtiff

libtiff's newer version doesn't need the --without-apple-opengl-framework
configure switch, so delete that as well.
Update hicolor-icon-theme

Version 0.13 does support non-srcdir builds, so remove that flag.
Update gettext-runtime

This version doesn't need the patch for bug 33999 anymore, so we can
remove that patch file.
Add itstool

This is a quite common build dependency in Gnome lately.
Update gtk-doc, replace gnome-doc-utils with yelp

The latest gtk-doc needs itstool and libxml2, so it needs to go into
gtk-osx-bootstrap.modules.

The gnome-doc-utils module has been superseded by yelp-tools and
yelp-xsl.
Update comments on 10.10 versions of tools