Various design improvements (#42)

There are a couple of minor improvements which customers solve at the moment with various hacks and should be part of the theme instead.

* Removed max-width from card excerpt

* Updated custom theme settings

- Added show/hide "Read more" section in posts
- Added drop-cap option for posts
- Added show/hide metadata for posts

* Added lock icon for members-only posts on list

* Updated excerpt logic to work with access levels

* Fixing missing id's for input fields

* Updated secondary color contrast

partials/icons/lock.hbs

@@ -1,5 +1 @@
-<svg width="20" height="20" viewBox="0 0 20 20" fill="none" xmlns="http://www.w3.org/2000/svg">
-    <path d="M16.25 6.875H3.75C3.40482 6.875 3.125 7.15482 3.125 7.5V16.25C3.125 16.5952 3.40482 16.875 3.75 16.875H16.25C16.5952 16.875 16.875 16.5952 16.875 16.25V7.5C16.875 7.15482 16.5952 6.875 16.25 6.875Z" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"></path>
-    <path d="M7.1875 6.875V4.0625C7.1875 3.31658 7.48382 2.60121 8.01126 2.07376C8.53871 1.54632 9.25408 1.25 10 1.25C10.7459 1.25 11.4613 1.54632 11.9887 2.07376C12.5162 2.60121 12.8125 3.31658 12.8125 4.0625V6.875" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"></path>
-    <path d="M10 13.125C10.6904 13.125 11.25 12.5654 11.25 11.875C11.25 11.1846 10.6904 10.625 10 10.625C9.30964 10.625 8.75 11.1846 8.75 11.875C8.75 12.5654 9.30964 13.125 10 13.125Z" fill="currentColor"></path>
-</svg>
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 20 20" height="20" width="20" id="Lock-1--Streamline-Ultimate"><defs></defs><title>lock-1</title><path d="M4.375 8.125h11.25s1.25 0 1.25 1.25v8.75s0 1.25 -1.25 1.25H4.375s-1.25 0 -1.25 -1.25v-8.75s0 -1.25 1.25 -1.25" fill="none" stroke="currentcolor" stroke-linecap="round" stroke-linejoin="round" stroke-width="1.5"></path><path d="M5.625 8.125V5a4.375 4.375 0 0 1 8.75 0v3.125" fill="none" stroke="currentcolor" stroke-linecap="round" stroke-linejoin="round" stroke-width="1.5"></path><path d="m10 12.5 0 2.5" fill="none" stroke="currentcolor" stroke-linecap="round" stroke-linejoin="round" stroke-width="1.5"></path></svg>