adds new source 'Plex Library' with Auto Director and Auto Actor collection sub-types, option to configure minimum items. utilises smart collections. adds new poster template. adds separators option.
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Co-authored-by: Tom Wheeler <thomas.wheeler.tcw@gmail.com>
Adds poster template import/export function, including required assets (ZIP). Adds import/export of
source colours (JSON). Refactored elements into unified system. Added elements layering. Added
canvas for accurate text measurements. Added fonts. Changed dockerfile to build with debian for
dependencies. Added poster files for quicker generation of poster previews.
