Fixed segfault
Following symlinks in run-dflat.sh.

Thanks to Michael.
Small change in MSO encoding.

For deriving incomplete/1, we now consider the current assignment, not
the one in the child item tree.
Added check to UncompressedItemTree
Fixed error in QSAT encoding.

It occurred when rejecting children of OR nodes were pruned in such a way
that the remaining children of these OR nodes did not match in a join node. This led to the correct "reject" not being performed.
Added modeline capability.

If the first line of an ASP encoding starts with "%dflat: ", the rest of
that line is added to the D-FLAT command-line options.
--no-pruning now prunes in the TD root.

Otherwise there are sometimes wrong results in, e.g., QSAT.
Adapted VC encodings to newest clingo syntax.

Also adapted test_optval scripts to new D-FLAT output.
Moved UncompressedItemTree to global namespace (from solver::asp::trees)
Added constant 'numChildNodes' and fact 'initial' to user encoding input
Fixed default join
Adapted exchange program for Vertex Cover
Better progress report.
Deriving '-leaf' is obsolete since we have 'initial'.
Moved to clasp 3.0.0
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