v3.7.0: Dropping zc157, adding carousels and bugfixes

This major release contains changes associated with the following GitHub issues:

#160: Refactor/sync layout of the various product_xx_info templates
#285: Price displays twice when a product includes attributes.
#291: Include a home-page slider
#292: Checkout Shipping shows "Continue" to Step 2 Payment, when not available/no shipping allowed
#308: Correct 'misuse' of <main> tag.
#358: Update to use FA-6, allow preloading to be disabled.
#359: Correct product-listing/category-row display for 'columns' display
#360: Enable the exclusion of no-product categories from the categories' sidebox and upper navigation.
#362: Drop support for Zen Cart versions prior to 1.5.8.
#363: Correct MySQL/ANSI-mode issues.
#365: Incorporate zc158 changes to the attributes' display.
#367: Correct the SQL uninstall script for the Bootstrap Colors configuration.
#369: Enable different container types for header/main-content/footer.
#370: <meta charset must precede preload links; HTML validation issue.
#371: zca_rating_stars always outputs 5 stars.
#372: Enable a carousel display on various sideboxes.
#375: Enable carousel display on new, featured and specials centerboxes, they can either 'fade' or 'slide'.
#377: Add jquery.matchHeight{.min}.js to address jiggly bits on sidebox/centerbox carousels.
#380: Correct checkout_confirm coloring (was using those for checkout_continue).
#384: Include zc201 notifications for sideboxes ('information', 'more_information', 'ezpages').
#385: Move header-messages to below logo; they were being overlaid by the fixed-top navigation.