Fix Paolo email address again

That should be right now
build: lower gio and libxml2 requirements for wixl

These versions are present in RHEL6.  However, there is still
an undefined reference to g_hash_table_add.
wixl: do not use g_hash_table_add

This is not supported in GLib 2.22, which is the version used in RHEL6.
build: libuuid dependency is now mandatory

This was just a hack because Fedora mingw does not have a libuuid
port.  It can go.  And we can also always build wixl.
build: add dist-xz
msibuild: add missing include file
libmsi: guard calls of parent class constructed method

RHEL6's glib 2.22 leaves a NULL pointer there.
wixl: add --wxidir option