Improved Iterative Deepening Searcher #885

Job	Run time
clang-format	6m 23s
Coverage (STP)	47m 20s
Linux (LLVM 14)	15m 13s
Coverage (Z3)	49m 49s
Docker	13m 8s
macOS	11m 3s
Linux (LLVM 13)	15m 13s
Linux (LLVM 12)	15m 14s
Linux (LLVM 11, Doxygen)	15m 14s
Linux (LLVM 10)	15m 13s
Linux (LLVM 9)	15m 13s
Linux (ASan)	15m 14s
Linux (UBSan)	7m 3s
Linux (MSan)	15m 11s
Linux (Z3 only)	8m 44s
Linux (metaSMT)	15m 14s
Linux (STP master)	15m 15s
Linux (Latest klee-uclibc)	15m 13s
Linux (Asserts disabled)	15m 12s
Linux (No TCMalloc, optimised runtime)	14m 54s
	5h 41m 3s

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