first attempt of syntax plugins

The first version of the new plugin system. Syntax plugins only yet. A very simple
example plugin called info (doing nothig useful yet) is included.

Missing Features

  - Doku_Block_Handler needs work (doesn't honur plugins yet)
  - there is no way to specify the order of plugins and other modes yet
  - useful output from the info plugin
  - bug testing and fixing
  - code cleanup
  - documentation

darcs-hash:20050519201009-9977f-f793dbfc6a39d8a9643b610927d93cd3288bdd6b.gz