Use Helpers for fields and actions

First merge #109.

 - Fields refactored to helpers
   Nameconvention for fields from other plugins
     - `<pluginname>_<componentname>` (recognized by underscore)

 - Actions refactored to helpers
   Name convention for actions from other plugins
    - `<pluginname>_<componentname>` (recognized by underscore)
    - shortcut notation `<actionname>` which is translated to `<actionname>_<actionname>`  (supports plugins with component name equal to plugin name, so only one component per plugin possible.

Note: I have added some hardcode warning messages, which request updating of data and pagemod plugin. Opinions about this?

I have prepared Data plugin and Pagemod plugin for this new mechanism as well.