Implement Pascal Fontaine's congruence closure and Dijkstra's shortest path algorithms. Also implement required data-structures. Change minor things with formulas and expressions to correctly handle equations.

Data-structures for congruence closure:
- CCR (congruence class record): stores information about congruence classes
- FindTable: HashMap to store and quickly access representatives of terms
- SignatureTable: Store signatures and their current representatives

Data-structures for Dijkstra algorithm:
- WGraph: directed, weighted, labeled graph; Label are sets
- PathTree: tree structure corresponding to shortest paths in congruence graph
- MyPriorityQueue: priority queue with decrease-key function
Merge branch 'congruence' of https://github.com/AFellner/Skeptik into congruence

Conflicts:
	src/main/scala/at/logic/skeptik/parser/ProofParserVeriT.scala
Update job file
Merge branch 'Skeptik-upstream/develop'

Conflicts:
	src/main/scala/at/logic/skeptik/parser/ProofParserVeriT.scala
Remove some small bugfixes in congruence and add tests for shorter explanations
Make congruence classes immutable and add draft of compression algorithm
Change PathTree to EquationTree with specific types of labels and vertices
Make EquationTree proof producing, introduce Congruence inference types
Change eqC(i) to eqC(o) and improve CongruenceCompressor
Remove Bugs from Congruence and proof production of EqualityTree
Make equations recognised symmetrically when resolving nodes, gather and resolve produced subproofs with inequalities
Collect references of equations and use them in proof production. Export buggy proof and import again throws exception.
Change SMT FileExporter to begin with clause .c1 instead of .c0
Make ProofParserVeriT's resolution method invariant to clause permutations
Implement different version of proof production with long transitivity chains and experiment with R.apply
Introduce EqW class as a wrapper for equalities and add comments to CCR, congruence and CongruenceCompressor
Add resolve bugs to experiments
Clean up code and add comments, mostly in the at.logic.skeptik.algorithms.congruence package.
Include comments in EquationPath, WGraph and at.logic.skeptik.proof.sequent.lk.congruence, rename EquationTree to EquationPath

remove allEqs method from EquationPath
Merge