Created README

Just containing a short summary and referring to the website.
Improved SAT instance generators.
Updated some test scripts
Declared all make targets as phony.

This fixes a problem when there are files with the same name as the
target (like "all", "debug", etc.) in the root directory.
Google unit test framework and some simple tests
Minor clean-up
Added tests for Module
Now using gringo 4.3.0
Updated INSTALL file
Added copyright information to unit tests.
Raisisng error when not supplying -e
Copyright notice: 2013 -> 2014
Voodoo in libclasp again...
Forgot to call storeAtom() in printSymbol()
Using clasp 3.0.1
Updated to clasp 3.0.2
Added rudimentary checks on ASP encoding (not in table mode for now)
Added tests for DirectedAcyclicGraph
Made DirectedAcyclicGraph comply with tests
Tests for ItemTreeNode