0.18 released

[Mike McTernan]

Changes:

0.18: 30/08/2010
Fix bad strncat() use allowing possible overrun.
Thanks to ensc42 and Neils for finding this.
Fix multi-line labels causing multiple dividers ("---")
Thanks to llucax for the report, issue #31.
Add support for arrowless arcs and bi-directional arrows as
requested
by xmlscott and started by Niels. Can now use arrows such as <-
>, <=>
for bidirectional arrows, --, ==, .. etc... for arcs without
arrows.
Issue #29.
Fix text rendering over the box edge in multiline labels.
Add patch to honour linecolour in boxes, issue #33.
Thanks to Neils for this patch.
Add 'textbgcolour' and 'arctextbgcolour' attributes to set the
background colour for text in an entity or on an arc.
Add support for -X and X- arcs which indicate a lost message.
Add support for a new 'arcskip' attribute which allows an arc to
have
an additional slant to show delays or similar.
Change configure.ac to attempt to use gdlib-config and then pkg-
config.
This enables simpler configuration/build on platforms where gd
hasn't
been updated to supply a pkg-config file e.g. Cygwin. Update
README
regarding building on Cygwin and progress the cygport.

--
Mike