Create a pluginConsumer/Provider pattern interface, s.t. users can add {{plugin}} handlers and remove user-defined functions (i.e., plugin_functionname) from lib/plugins, since there from now on only real tokens should be stored #43
Add a test user-defined token, and see if it gets loaded #44
KEEP THIS JUST AS IS:
1) Plugins have always the same syntax {{plugin|param}} and are stored in wiki/plugins
2) Tokens have only one folder wiki/tokens where we store both: user-defined and build-in tokens
Find two distinct names for this two concepts.