Improve HTML plan, some minor fixes, fast setting updates

What's Changed

• Fix units on calculate_plan_every by @springfall2008 in #710
• Update settings right away rather than waiting for HA run by @springfall2008 in #711
• Add symbols in the plan for different rate sources by @springfall2008 in #712
• Set max charge/discharge rate fuzzy threshold to be max_rate/25 rather than hard-wired to 100 by @springfall2008 in #715
• Show creation time on html plan by @springfall2008 in #716
• Detect GE inverter in calibration mode, fix to previous charge/discharge rate code by @springfall2008 in #717

Full Changelog: v7.15.12...v7.15.13