Added blending and lexicographic handling of multiple linear objectives #2325

Job	Run time
debug (macos-latest)	11m 19s
debug_all_tests (macos-latest)	10m 21s
debug64_all_tests (macos-latest)	14m 11s
debug64 (macos-latest)	9m 44s
release_all_tests (macos-latest)	6m 25s
release (macos-latest)	6m 13s
Release64 (macos-latest)	5m 57s
Release64_all_tests (macos-latest)	12m 35s
	1h 16m 45s

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