#563 - dynamically load dark theme color constants

src/main/resources/templates/about.ftl

src/main/resources/templates/accounts/accounts.ftl

src/main/resources/templates/accounts/newAccount.ftl

src/main/resources/templates/categories/categories.ftl

src/main/resources/templates/categories/newCategory.ftl

src/main/resources/templates/charts/charts.ftl

src/main/resources/templates/charts/manage.ftl

src/main/resources/templates/charts/newChart.ftl

src/main/resources/templates/error/400.ftl

src/main/resources/templates/error/403.ftl

src/main/resources/templates/error/404.ftl

src/main/resources/templates/error/418.ftl

src/main/resources/templates/error/500.ftl

src/main/resources/templates/firstUse.ftl

src/main/resources/templates/helpers/header.ftl

src/main/resources/templates/hotkeys.ftl

src/main/resources/templates/index.ftl

src/main/resources/templates/login.ftl

src/main/resources/templates/placeholder/comingSoon.ftl

src/main/resources/templates/placeholder/emptyPage.ftl