Improvements to emap - Githubissues

This PR contains improvements to emap:

Adding alternative best matches to improve area recovery
Adding custom arrival and required times
Adding a ignore_symmetries option to tech_library for super fast mapping with limited delay increase
Changing dropping phase heuristics (decrease the number of used inverters)
Tuning estimated references and inverter insertion
Removing deprecated methods
Fix delay inaccuracy with structural matching
Fix rare delay changes when using multi-output gates

lsils / mockturtle