More flexible variable refinement - direct field refinement, operator refinement

src/main/scala/insynth/InSynth.scala

src/main/scala/insynth/leon/loader/Loader.scala

src/main/scala/insynth/leon/loader/PreLoader.scala

src/main/scala/lesynth/ExampleRunner.scala

src/main/scala/lesynth/Refiner.scala

src/main/scala/lesynth/Report.scala

src/main/scala/lesynth/SynthesisInfo.scala

src/main/scala/lesynth/SynthesizerExamples.scala

src/main/scala/lesynth/VariableRefiner.scala

...a/lesynth/rules/ConditionAbductionSynthesisTwoPhase.scala

src/test/scala/lesynth/VariableRefinerTest.scala