build: explicitely include libcmpl

While on archlinux libadg automatically pulls the libcmpl dependency, on
Ubuntu it must be explicitely set, otherwise the link will fail.
build: uninstall also CPML link from NSis
adg: added dash patterns to line stroking

Wrapped data needed for dashing lines in a GBoxed struct (AdgDash) and
provided necessary changes to AdgLineStyle. Some new builtins dresses
are now available, most notably ADG_DRESS_LINE_AXIS and
ADG_DRESS_LINE_HIDDEN.

Closes issue #51: http://dev.entidi.com/p/adg/issues/51/