Fix GUI message consistency, restore signal-handler checkpointing, and update documentation image#3301

vaughnbetz merged 5 commits intomasterverilog-to-routing/vtr-verilog-to-routing:masterfrom

update_images_and_gui_messageverilog-to-routing/vtr-verilog-to-routing:update_images_and_gui_messageCopy head branch name to clipboard