Ignore sentences where text exists in symbol

Tried to check if sentence text is equivalent to entity text. If so, do
not create respective sentence. Note: Does not work so far because
text-syntax in the affected colums is slightly different and hardly to
be generalized.
Don't repeat sentence name in sentence text
put context in block
Rev "Ignore sentences where text exists in symbol"

reported for hets, see http://trac.informatik.uni-bremen.de:8080/hets/ticket/1101

This reverts commit 38ff4b3e26780dc16fa0ef9e0fe99bb8238619dc.
began readability module for sentences
Merge branch 'master' into display_of_axioms
finished test for display of sentences, began model
generate logic-mapping-graph with JIT see #138
logic-graph with depth see #138
unmess code and improve visibility of jit-graph
LogicMappings-graph in both directions
use thejit as gem and add context-menu
Set display_text on sentences from update_or_create_from_hash.
use coffeescript
use jit only when needed
add sql-based method for determining graph nodes.
Merge branch 'master' into graphs
adjust logic-fetching sql for logic-graph-nodes

- Use With-Clause instead of temporary
  table (Select Into).
remove mysql-gem from Gemfile

- We actually use PostgreSQL now, so
  we don't need the mysql-gem anymore.
Extract graph-data fetching into own class

- Since we can reuse the idea for fetching
  the graphs nodes in ontologies, this
  extracts the functionality into
  its own flexible class.