v0.2.2: New labels & more improvements

• New: Label design (#35)
• New: Entity name now visible in title when graph point is hovered over (#39)
• New: hover parameter for labels
• New: Now rendering missing history as a horizontal line up to the first available history entry (similar to the default history-graph)
• Change: Made labels visible on hover by default
• Change: Label font size now has a min size and scales relative to the font_size option
• Fixed: Significantly improved accuracy of graph point values
• Fixed: Only fetch history for updated entities, use cache to update rest
• Fixed: Graph points not applying threshold color from line_color_above / line_color_below (#38)
• Fixed: Invalid timestamps when combining points_per_hour & hours_to_show (#37, #36)
• Fixed: Misaligned legend text
• Fixed: Missing bottom padding when graph is hidden
• Fixed: Invisible lines when graph was updated after not covering the full width on load
• Fixed: Align timestamps right when align_state is set to right