Log Message:
Update to 0.5.18:

** The macro AX_CREATE_STDINT_H that is used to create idn-int.h
** has been updated.

** Fix use of 'head -1' in configure script (should be 'head -n -1'),
** thanks to Carsten Lohrke.

** Announce the help-libidn mailing list in documentation and README.

** Translation updates.

** API and ABI is backwards compatible with the previous version.