Added ctags file to .gitignore
Ability for plugins to add rules
Freeing of allocated memory
Cleanup
Made derp_assert_triple reentrant
Made derp_add_rule reentrant
More concise code in derp_add_rule
Changed Plugin API to use glib data types
Code clean up
Functions for adding/deleting triples, lists of triples and asserting rules
Simpler rule defintion using macros