Fixed the 'prereq' alias for the 'requires' parameter
Added some tests in t/basic.t to test the dependency checking
Added 'artistic' as a licensing option [Arthur Bergman]
Fixed some bugs in requires/prereq/recommends/conflicts/build_depends
Fixed a typo in the 'distclean' action that prevented its
execution [Arthur Bergman]Separated the linking phase of building XS items into its own
link_c() method. Its interface is still unstable, so it's not
documented yet. [suggested by Arthur Bergman]