Rework TableConvert-plugin to be a little more generic.
Purge unneeded code
Added testfiles
Fix possible memory leaks
Use correct callback function
Improve way how worker is being called. Thanks to b4n and elextr.
Fix a few small bugs.

* Change 'uint' typo to 'guint'.
* Change accidental hardcoded default_value.
* Add wrapper function for g_object_class_install_properties since
  it's only available since GLIB 2.26.
* Make PROP_O equal zero because it's always supposed to be zero.
Update HTML help file with slightly changed doc-utils output
Make rule-parameter const
Merge pull request #82 from frlan/Tableconvert_more_generic_rework

Tableconvert more generic rework
scope - documented changes by other developers