v2.3.4 fixes a sed compatibility issue, fixes a progressbar bug

Minor patching update:

• Some fringe implementations of sed do not expand escape character, so we need to expand it before passing it to sed. This caused arttime to not center colored art on OSes that used such sed, that is now fixed.
• Fixes a progress bar bug that would show up only when user paused and unpaused multiple times during a sprint. It made the progress bar shrink and then expand at a faster rate. That is now fixed.